diff --git a/Cargo.lock b/Cargo.lock
index 9a59e2ea8..8c3d76980 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1973,6 +1973,7 @@ dependencies = [
  "meilisearch-types",
  "nelson",
  "page_size 0.5.0",
+ "puffin",
  "roaring",
  "serde",
  "serde_json",
@@ -2498,6 +2499,12 @@ dependencies = [
  "syn 1.0.109",
 ]
 
+[[package]]
+name = "lz4_flex"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b8c72594ac26bfd34f2d99dfced2edfaddfe8a476e3ff2ca0eb293d925c4f83"
+
 [[package]]
 name = "manifest-dir-macros"
 version = "0.1.17"
@@ -2587,6 +2594,8 @@ dependencies = [
  "pin-project-lite",
  "platform-dirs",
  "prometheus",
+ "puffin",
+ "puffin_http",
  "rand",
  "rayon",
  "regex",
@@ -2731,6 +2740,7 @@ dependencies = [
  "obkv",
  "once_cell",
  "ordered-float",
+ "puffin",
  "rand",
  "rand_pcg",
  "rayon",
@@ -3256,6 +3266,35 @@ version = "2.28.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "106dd99e98437432fed6519dedecfade6a06a73bb7b2a1e019fdd2bee5778d94"
 
+[[package]]
+name = "puffin"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76425abd4e1a0ad4bd6995dd974b52f414fca9974171df8e3708b3e660d05a21"
+dependencies = [
+ "anyhow",
+ "bincode",
+ "byteorder",
+ "cfg-if",
+ "instant",
+ "lz4_flex",
+ "once_cell",
+ "parking_lot",
+ "serde",
+]
+
+[[package]]
+name = "puffin_http"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13bffc600c35913d282ae1e96a6ffcdf36dc7a7cdb9310e0ba15914d258c8193"
+dependencies = [
+ "anyhow",
+ "crossbeam-channel",
+ "log",
+ "puffin",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.28"
diff --git a/index-scheduler/Cargo.toml b/index-scheduler/Cargo.toml
index 36c28cd67..9e7c2ae4b 100644
--- a/index-scheduler/Cargo.toml
+++ b/index-scheduler/Cargo.toml
@@ -22,6 +22,7 @@ log = "0.4.17"
 meilisearch-auth = { path = "../meilisearch-auth" }
 meilisearch-types = { path = "../meilisearch-types" }
 page_size = "0.5.0"
+puffin = "0.16.0"
 roaring = { version = "0.10.1", features = ["serde"] }
 serde = { version = "1.0.160", features = ["derive"] }
 serde_json = { version = "1.0.95", features = ["preserve_order"] }
diff --git a/index-scheduler/src/batch.rs b/index-scheduler/src/batch.rs
index 2948e7506..fb865a98b 100644
--- a/index-scheduler/src/batch.rs
+++ b/index-scheduler/src/batch.rs
@@ -471,6 +471,8 @@ impl IndexScheduler {
         #[cfg(test)]
         self.maybe_fail(crate::tests::FailureLocation::InsideCreateBatch)?;
 
+        puffin::profile_function!();
+
         let enqueued = &self.get_status(rtxn, Status::Enqueued)?;
         let to_cancel = self.get_kind(rtxn, Kind::TaskCancelation)? & enqueued;
 
@@ -575,6 +577,9 @@ impl IndexScheduler {
             self.maybe_fail(crate::tests::FailureLocation::PanicInsideProcessBatch)?;
             self.breakpoint(crate::Breakpoint::InsideProcessBatch);
         }
+
+        puffin::profile_function!(format!("{:?}", batch));
+
         match batch {
             Batch::TaskCancelation { mut task, previous_started_at, previous_processing_tasks } => {
                 // 1. Retrieve the tasks that matched the query at enqueue-time.
@@ -1111,6 +1116,8 @@ impl IndexScheduler {
         index: &'i Index,
         operation: IndexOperation,
     ) -> Result<Vec<Task>> {
+        puffin::profile_function!();
+
         match operation {
             IndexOperation::DocumentClear { mut tasks, .. } => {
                 let count = milli::update::ClearDocuments::new(index_wtxn, index).execute()?;
diff --git a/index-scheduler/src/lib.rs b/index-scheduler/src/lib.rs
index 092851edd..fc5a8a0f9 100644
--- a/index-scheduler/src/lib.rs
+++ b/index-scheduler/src/lib.rs
@@ -1032,6 +1032,8 @@ impl IndexScheduler {
             self.breakpoint(Breakpoint::Start);
         }
 
+        puffin::GlobalProfiler::lock().new_frame();
+
         self.cleanup_task_queue()?;
 
         let rtxn = self.env.read_txn().map_err(Error::HeedTransaction)?;
diff --git a/meilisearch/Cargo.toml b/meilisearch/Cargo.toml
index 7d6601ac5..1f51cea84 100644
--- a/meilisearch/Cargo.toml
+++ b/meilisearch/Cargo.toml
@@ -67,6 +67,8 @@ permissive-json-pointer = { path = "../permissive-json-pointer" }
 pin-project-lite = "0.2.9"
 platform-dirs = "0.3.0"
 prometheus = { version = "0.13.3", features = ["process"] }
+puffin = "0.16.0"
+puffin_http = "0.13.0"
 rand = "0.8.5"
 rayon = "1.7.0"
 regex = "1.7.3"
diff --git a/meilisearch/src/main.rs b/meilisearch/src/main.rs
index d6b9f027d..5189113ad 100644
--- a/meilisearch/src/main.rs
+++ b/meilisearch/src/main.rs
@@ -29,6 +29,9 @@ fn setup(opt: &Opt) -> anyhow::Result<()> {
 async fn main() -> anyhow::Result<()> {
     let (opt, config_read_from) = Opt::try_build()?;
 
+    puffin::set_scopes_on(true);
+    let _server = puffin_http::Server::new(&format!("0.0.0.0:{}", puffin_http::DEFAULT_PORT))?;
+
     anyhow::ensure!(
         !(cfg!(windows) && opt.experimental_reduce_indexing_memory_usage),
         "The `experimental-reduce-indexing-memory-usage` flag is not supported on Windows"
diff --git a/milli/Cargo.toml b/milli/Cargo.toml
index ce3070e5d..80b0a5f86 100644
--- a/milli/Cargo.toml
+++ b/milli/Cargo.toml
@@ -67,6 +67,9 @@ filter-parser = { path = "../filter-parser" }
 # documents words self-join
 itertools = "0.10.5"
 
+# profiling
+puffin = "0.16.0"
+
 # logging
 log = "0.4.17"
 logging_timer = "1.1.0"
diff --git a/milli/src/update/clear_documents.rs b/milli/src/update/clear_documents.rs
index 5fdf8ef49..c021647ee 100644
--- a/milli/src/update/clear_documents.rs
+++ b/milli/src/update/clear_documents.rs
@@ -15,6 +15,8 @@ impl<'t, 'u, 'i> ClearDocuments<'t, 'u, 'i> {
     }
 
     pub fn execute(self) -> Result<u64> {
+        puffin::profile_function!();
+
         self.index.set_updated_at(self.wtxn, &OffsetDateTime::now_utc())?;
         let Index {
             env: _env,
diff --git a/milli/src/update/delete_documents.rs b/milli/src/update/delete_documents.rs
index c9124e591..48415adef 100644
--- a/milli/src/update/delete_documents.rs
+++ b/milli/src/update/delete_documents.rs
@@ -110,6 +110,8 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
         Some(docid)
     }
     pub fn execute(self) -> Result<DocumentDeletionResult> {
+        puffin::profile_function!();
+
         let DetailedDocumentDeletionResult { deleted_documents, remaining_documents } =
             self.execute_inner()?;
 
diff --git a/milli/src/update/index_documents/enrich.rs b/milli/src/update/index_documents/enrich.rs
index 09599ac82..35a7c33f3 100644
--- a/milli/src/update/index_documents/enrich.rs
+++ b/milli/src/update/index_documents/enrich.rs
@@ -31,6 +31,8 @@ pub fn enrich_documents_batch<R: Read + Seek>(
     autogenerate_docids: bool,
     reader: DocumentsBatchReader<R>,
 ) -> Result<StdResult<EnrichedDocumentsBatchReader<R>, UserError>> {
+    puffin::profile_function!();
+
     let (mut cursor, mut documents_batch_index) = reader.into_cursor_and_fields_index();
 
     let mut external_ids = tempfile::tempfile().map(grenad::Writer::new)?;
diff --git a/milli/src/update/index_documents/extract/extract_docid_word_positions.rs b/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
index 8985534db..f726bf866 100644
--- a/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
+++ b/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
@@ -30,6 +30,8 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     stop_words: Option<&fst::Set<&[u8]>>,
     max_positions_per_attributes: Option<u32>,
 ) -> Result<(RoaringBitmap, grenad::Reader<File>, ScriptLanguageDocidsMap)> {
+    puffin::profile_function!();
+
     let max_positions_per_attributes = max_positions_per_attributes
         .map_or(MAX_POSITION_PER_ATTRIBUTE, |max| max.min(MAX_POSITION_PER_ATTRIBUTE));
     let max_memory = indexer.max_memory_by_thread();
diff --git a/milli/src/update/index_documents/extract/extract_facet_number_docids.rs b/milli/src/update/index_documents/extract/extract_facet_number_docids.rs
index 33dd5ce5b..dec02b120 100644
--- a/milli/src/update/index_documents/extract/extract_facet_number_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_facet_number_docids.rs
@@ -20,6 +20,8 @@ pub fn extract_facet_number_docids<R: io::Read + io::Seek>(
     docid_fid_facet_number: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut facet_number_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_facet_string_docids.rs b/milli/src/update/index_documents/extract/extract_facet_string_docids.rs
index 0d9c0981e..e5e864b66 100644
--- a/milli/src/update/index_documents/extract/extract_facet_string_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_facet_string_docids.rs
@@ -18,6 +18,8 @@ pub fn extract_facet_string_docids<R: io::Read + io::Seek>(
     docid_fid_facet_string: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut facet_string_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs b/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
index 77a5561fe..882d7779f 100644
--- a/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
+++ b/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
@@ -34,6 +34,8 @@ pub fn extract_fid_docid_facet_values<R: io::Read + io::Seek>(
     indexer: GrenadParameters,
     faceted_fields: &HashSet<FieldId>,
 ) -> Result<ExtractedFacetValues> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut fid_docid_facet_numbers_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
index fe8eb93ed..79cf4c7fe 100644
--- a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
@@ -22,6 +22,8 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut fid_word_count_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_geo_points.rs b/milli/src/update/index_documents/extract/extract_geo_points.rs
index ddb38abe5..139e8230a 100644
--- a/milli/src/update/index_documents/extract/extract_geo_points.rs
+++ b/milli/src/update/index_documents/extract/extract_geo_points.rs
@@ -19,6 +19,8 @@ pub fn extract_geo_points<R: io::Read + io::Seek>(
     primary_key_id: FieldId,
     (lat_fid, lng_fid): (FieldId, FieldId),
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let mut writer = create_writer(
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
diff --git a/milli/src/update/index_documents/extract/extract_vector_points.rs b/milli/src/update/index_documents/extract/extract_vector_points.rs
index 0fad3be07..69fbff9b5 100644
--- a/milli/src/update/index_documents/extract/extract_vector_points.rs
+++ b/milli/src/update/index_documents/extract/extract_vector_points.rs
@@ -19,6 +19,8 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
     primary_key_id: FieldId,
     vectors_fid: FieldId,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let mut writer = create_writer(
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
diff --git a/milli/src/update/index_documents/extract/extract_word_docids.rs b/milli/src/update/index_documents/extract/extract_word_docids.rs
index da59f9dde..f1656d024 100644
--- a/milli/src/update/index_documents/extract/extract_word_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_docids.rs
@@ -27,6 +27,8 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
     indexer: GrenadParameters,
     exact_attributes: &HashSet<FieldId>,
 ) -> Result<(grenad::Reader<File>, grenad::Reader<File>)> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut word_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_word_fid_docids.rs b/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
index 9ee33ea0d..aaf8fad79 100644
--- a/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
@@ -15,6 +15,8 @@ pub fn extract_word_fid_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut word_fid_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
index 6707fc268..4c910f32e 100644
--- a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
@@ -21,6 +21,8 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut word_pair_proximity_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_word_position_docids.rs b/milli/src/update/index_documents/extract/extract_word_position_docids.rs
index 9bb43b004..e945833e6 100644
--- a/milli/src/update/index_documents/extract/extract_word_position_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_position_docids.rs
@@ -18,6 +18,8 @@ pub fn extract_word_position_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<File>> {
+    puffin::profile_function!();
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut word_position_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/mod.rs b/milli/src/update/index_documents/extract/mod.rs
index 6259c7272..1b1dc1420 100644
--- a/milli/src/update/index_documents/extract/mod.rs
+++ b/milli/src/update/index_documents/extract/mod.rs
@@ -52,6 +52,8 @@ pub(crate) fn data_from_obkv_documents(
     max_positions_per_attributes: Option<u32>,
     exact_attributes: HashSet<FieldId>,
 ) -> Result<()> {
+    puffin::profile_function!();
+
     original_obkv_chunks
         .par_bridge()
         .map(|original_documents_chunk| {
@@ -238,11 +240,13 @@ fn spawn_extraction_task<FE, FS, M>(
     M::Output: Send,
 {
     rayon::spawn(move || {
+        puffin::profile_scope!("extract_multiple_chunks", name);
         let chunks: Result<M> =
             chunks.into_par_iter().map(|chunk| extract_fn(chunk, indexer)).collect();
         rayon::spawn(move || match chunks {
             Ok(chunks) => {
                 debug!("merge {} database", name);
+                puffin::profile_scope!("merge_multiple_chunks", name);
                 let reader = chunks.merge(merge_fn, &indexer);
                 let _ = lmdb_writer_sx.send(reader.map(serialize_fn));
             }
diff --git a/milli/src/update/index_documents/helpers/grenad_helpers.rs b/milli/src/update/index_documents/helpers/grenad_helpers.rs
index eb66a28fe..d5f5ac0bd 100644
--- a/milli/src/update/index_documents/helpers/grenad_helpers.rs
+++ b/milli/src/update/index_documents/helpers/grenad_helpers.rs
@@ -214,6 +214,7 @@ pub fn sorter_into_lmdb_database(
     sorter: Sorter<MergeFn>,
     merge: MergeFn,
 ) -> Result<()> {
+    puffin::profile_function!();
     debug!("Writing MTBL sorter...");
     let before = Instant::now();
 
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 20a36237e..1b2aab827 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -137,6 +137,8 @@ where
         mut self,
         reader: DocumentsBatchReader<R>,
     ) -> Result<(Self, StdResult<u64, UserError>)> {
+        puffin::profile_function!();
+
         // Early return when there is no document to add
         if reader.is_empty() {
             return Ok((self, Ok(0)));
@@ -175,6 +177,8 @@ where
         mut self,
         to_delete: Vec<String>,
     ) -> Result<(Self, StdResult<u64, UserError>)> {
+        puffin::profile_function!();
+
         // Early return when there is no document to add
         if to_delete.is_empty() {
             return Ok((self, Ok(0)));
@@ -194,6 +198,8 @@ where
 
     #[logging_timer::time("IndexDocuments::{}")]
     pub fn execute(mut self) -> Result<DocumentAdditionResult> {
+        puffin::profile_function!();
+
         if self.added_documents == 0 {
             let number_of_documents = self.index.number_of_documents(self.wtxn)?;
             return Ok(DocumentAdditionResult { indexed_documents: 0, number_of_documents });
@@ -232,6 +238,8 @@ where
         FP: Fn(UpdateIndexingStep) + Sync,
         FA: Fn() -> bool + Sync,
     {
+        puffin::profile_function!();
+
         let TransformOutput {
             primary_key,
             fields_ids_map,
@@ -322,6 +330,7 @@ where
 
         // Run extraction pipeline in parallel.
         pool.install(|| {
+            puffin::profile_scope!("extract_and_send_grenad_chunks");
             // split obkv file into several chunks
             let original_chunk_iter =
                 grenad_obkv_into_chunks(original_documents, pool_params, documents_chunk_size);
@@ -477,6 +486,8 @@ where
         FP: Fn(UpdateIndexingStep) + Sync,
         FA: Fn() -> bool + Sync,
     {
+        puffin::profile_function!();
+
         // Merged databases are already been indexed, we start from this count;
         let mut databases_seen = MERGED_DATABASE_COUNT;
 
@@ -511,26 +522,36 @@ where
             return Err(Error::InternalError(InternalError::AbortedIndexation));
         }
 
-        let current_prefix_fst = self.index.words_prefixes_fst(self.wtxn)?;
+        let current_prefix_fst;
+        let common_prefix_fst_words_tmp;
+        let common_prefix_fst_words: Vec<_>;
+        let new_prefix_fst_words;
+        let del_prefix_fst_words;
 
-        // We retrieve the common words between the previous and new prefix word fst.
-        let common_prefix_fst_words = fst_stream_into_vec(
-            previous_words_prefixes_fst.op().add(&current_prefix_fst).intersection(),
-        );
-        let common_prefix_fst_words: Vec<_> = common_prefix_fst_words
-            .as_slice()
-            .linear_group_by_key(|x| x.chars().next().unwrap())
-            .collect();
+        {
+            puffin::profile_scope!("compute_prefix_diffs");
 
-        // We retrieve the newly added words between the previous and new prefix word fst.
-        let new_prefix_fst_words = fst_stream_into_vec(
-            current_prefix_fst.op().add(&previous_words_prefixes_fst).difference(),
-        );
+            current_prefix_fst = self.index.words_prefixes_fst(self.wtxn)?;
 
-        // We compute the set of prefixes that are no more part of the prefix fst.
-        let del_prefix_fst_words = fst_stream_into_hashset(
-            previous_words_prefixes_fst.op().add(&current_prefix_fst).difference(),
-        );
+            // We retrieve the common words between the previous and new prefix word fst.
+            common_prefix_fst_words_tmp = fst_stream_into_vec(
+                previous_words_prefixes_fst.op().add(&current_prefix_fst).intersection(),
+            );
+            common_prefix_fst_words = common_prefix_fst_words_tmp
+                .as_slice()
+                .linear_group_by_key(|x| x.chars().next().unwrap())
+                .collect();
+
+            // We retrieve the newly added words between the previous and new prefix word fst.
+            new_prefix_fst_words = fst_stream_into_vec(
+                current_prefix_fst.op().add(&previous_words_prefixes_fst).difference(),
+            );
+
+            // We compute the set of prefixes that are no more part of the prefix fst.
+            del_prefix_fst_words = fst_stream_into_hashset(
+                previous_words_prefixes_fst.op().add(&current_prefix_fst).difference(),
+            );
+        }
 
         databases_seen += 1;
         (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
@@ -668,6 +689,8 @@ fn execute_word_prefix_docids(
     common_prefix_fst_words: &[&[String]],
     del_prefix_fst_words: &HashSet<Vec<u8>>,
 ) -> Result<()> {
+    puffin::profile_function!();
+
     let cursor = reader.into_cursor()?;
     let mut builder = WordPrefixDocids::new(txn, word_docids_db, word_prefix_docids_db);
     builder.chunk_compression_type = indexer_config.chunk_compression_type;
diff --git a/milli/src/update/index_documents/transform.rs b/milli/src/update/index_documents/transform.rs
index ee6831be5..7a0c811a8 100644
--- a/milli/src/update/index_documents/transform.rs
+++ b/milli/src/update/index_documents/transform.rs
@@ -558,6 +558,8 @@ impl<'a, 'i> Transform<'a, 'i> {
     where
         F: Fn(UpdateIndexingStep) + Sync,
     {
+        puffin::profile_function!();
+
         let primary_key = self
             .index
             .primary_key(wtxn)?
diff --git a/milli/src/update/index_documents/typed_chunk.rs b/milli/src/update/index_documents/typed_chunk.rs
index 3f197fbd1..96dea0480 100644
--- a/milli/src/update/index_documents/typed_chunk.rs
+++ b/milli/src/update/index_documents/typed_chunk.rs
@@ -49,6 +49,66 @@ pub(crate) enum TypedChunk {
     ScriptLanguageDocids(HashMap<(Script, Language), RoaringBitmap>),
 }
 
+impl TypedChunk {
+    pub fn to_debug_string(&self) -> String {
+        match self {
+            TypedChunk::FieldIdDocidFacetStrings(grenad) => {
+                format!("FieldIdDocidFacetStrings {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdDocidFacetNumbers(grenad) => {
+                format!("FieldIdDocidFacetNumbers {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::Documents(grenad) => {
+                format!("Documents {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdWordcountDocids(grenad) => {
+                format!("FieldIdWordcountDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::NewDocumentsIds(grenad) => {
+                format!("NewDocumentsIds {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => format!(
+                "WordDocids {{ word_docids_reader: {}, exact_word_docids_reader: {} }}",
+                word_docids_reader.len(),
+                exact_word_docids_reader.len()
+            ),
+            TypedChunk::WordPositionDocids(grenad) => {
+                format!("WordPositionDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::WordFidDocids(grenad) => {
+                format!("WordFidDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::WordPairProximityDocids(grenad) => {
+                format!("WordPairProximityDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdFacetStringDocids(grenad) => {
+                format!("FieldIdFacetStringDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdFacetNumberDocids(grenad) => {
+                format!("FieldIdFacetNumberDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdFacetExistsDocids(grenad) => {
+                format!("FieldIdFacetExistsDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdFacetIsNullDocids(grenad) => {
+                format!("FieldIdFacetIsNullDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::FieldIdFacetIsEmptyDocids(grenad) => {
+                format!("FieldIdFacetIsEmptyDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::GeoPoints(grenad) => {
+                format!("GeoPoints {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::VectorPoints(grenad) => {
+                format!("VectorPoints {{ number_of_entries: {} }}", grenad.len())
+            }
+            TypedChunk::ScriptLanguageDocids(grenad) => {
+                format!("ScriptLanguageDocids {{ number_of_entries: {} }}", grenad.len())
+            }
+        }
+    }
+}
+
 /// Write typed chunk in the corresponding LMDB database of the provided index.
 /// Return new documents seen.
 pub(crate) fn write_typed_chunk_into_index(
@@ -57,6 +117,8 @@ pub(crate) fn write_typed_chunk_into_index(
     wtxn: &mut RwTxn,
     index_is_empty: bool,
 ) -> Result<(RoaringBitmap, bool)> {
+    puffin::profile_function!(typed_chunk.to_debug_string());
+
     let mut is_merged_database = false;
     match typed_chunk {
         TypedChunk::Documents(obkv_documents_iter) => {
@@ -336,6 +398,8 @@ where
     FS: for<'a> Fn(&'a [u8], &'a mut Vec<u8>) -> Result<&'a [u8]>,
     FM: Fn(&[u8], &[u8], &mut Vec<u8>) -> Result<()>,
 {
+    puffin::profile_function!(format!("number of entries: {}", data.len()));
+
     let mut buffer = Vec::new();
     let database = database.remap_types::<ByteSlice, ByteSlice>();
 
@@ -378,6 +442,8 @@ where
     FS: for<'a> Fn(&'a [u8], &'a mut Vec<u8>) -> Result<&'a [u8]>,
     FM: Fn(&[u8], &[u8], &mut Vec<u8>) -> Result<()>,
 {
+    puffin::profile_function!(format!("number of entries: {}", data.len()));
+
     if !index_is_empty {
         return write_entries_into_database(
             data,
diff --git a/milli/src/update/prefix_word_pairs/mod.rs b/milli/src/update/prefix_word_pairs/mod.rs
index bed542bdb..3105b16e4 100644
--- a/milli/src/update/prefix_word_pairs/mod.rs
+++ b/milli/src/update/prefix_word_pairs/mod.rs
@@ -50,6 +50,8 @@ impl<'t, 'u, 'i> PrefixWordPairsProximityDocids<'t, 'u, 'i> {
         common_prefix_fst_words: &[&'a [String]],
         del_prefix_fst_words: &HashSet<Vec<u8>>,
     ) -> Result<()> {
+        puffin::profile_function!();
+
         index_word_prefix_database(
             self.wtxn,
             self.index.word_pair_proximity_docids,
diff --git a/milli/src/update/prefix_word_pairs/prefix_word.rs b/milli/src/update/prefix_word_pairs/prefix_word.rs
index 60e2e554e..1ec66d010 100644
--- a/milli/src/update/prefix_word_pairs/prefix_word.rs
+++ b/milli/src/update/prefix_word_pairs/prefix_word.rs
@@ -27,6 +27,8 @@ pub fn index_prefix_word_database(
     chunk_compression_type: CompressionType,
     chunk_compression_level: Option<u32>,
 ) -> Result<()> {
+    puffin::profile_function!();
+
     let max_proximity = max_proximity - 1;
     debug!("Computing and writing the word prefix pair proximity docids into LMDB on disk...");
 
diff --git a/milli/src/update/prefix_word_pairs/word_prefix.rs b/milli/src/update/prefix_word_pairs/word_prefix.rs
index db607e56c..570adece9 100644
--- a/milli/src/update/prefix_word_pairs/word_prefix.rs
+++ b/milli/src/update/prefix_word_pairs/word_prefix.rs
@@ -191,6 +191,7 @@ pub fn index_word_prefix_database(
     chunk_compression_type: CompressionType,
     chunk_compression_level: Option<u32>,
 ) -> Result<()> {
+    puffin::profile_function!();
     debug!("Computing and writing the word prefix pair proximity docids into LMDB on disk...");
 
     // Make a prefix trie from the common prefixes that are shorter than self.max_prefix_length
diff --git a/milli/src/update/settings.rs b/milli/src/update/settings.rs
index 5b8e5a21c..aebbbeca2 100644
--- a/milli/src/update/settings.rs
+++ b/milli/src/update/settings.rs
@@ -303,6 +303,8 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         FP: Fn(UpdateIndexingStep) + Sync,
         FA: Fn() -> bool + Sync,
     {
+        puffin::profile_function!();
+
         let fields_ids_map = self.index.fields_ids_map(self.wtxn)?;
         // if the settings are set before any document update, we don't need to do anything, and
         // will set the primary key during the first document addition.
diff --git a/milli/src/update/word_prefix_docids.rs b/milli/src/update/word_prefix_docids.rs
index b235c44a6..a30254994 100644
--- a/milli/src/update/word_prefix_docids.rs
+++ b/milli/src/update/word_prefix_docids.rs
@@ -45,6 +45,8 @@ impl<'t, 'u, 'i> WordPrefixDocids<'t, 'u, 'i> {
         common_prefix_fst_words: &[&[String]],
         del_prefix_fst_words: &HashSet<Vec<u8>>,
     ) -> Result<()> {
+        puffin::profile_function!();
+
         // It is forbidden to keep a mutable reference into the database
         // and write into it at the same time, therefore we write into another file.
         let mut prefix_docids_sorter = create_sorter(
diff --git a/milli/src/update/words_prefix_integer_docids.rs b/milli/src/update/words_prefix_integer_docids.rs
index 63ca178ef..c65438928 100644
--- a/milli/src/update/words_prefix_integer_docids.rs
+++ b/milli/src/update/words_prefix_integer_docids.rs
@@ -50,6 +50,7 @@ impl<'t, 'u, 'i> WordPrefixIntegerDocids<'t, 'u, 'i> {
         common_prefix_fst_words: &[&[String]],
         del_prefix_fst_words: &HashSet<Vec<u8>>,
     ) -> Result<()> {
+        puffin::profile_function!();
         debug!("Computing and writing the word levels integers docids into LMDB on disk...");
 
         let mut prefix_integer_docids_sorter = create_sorter(
diff --git a/milli/src/update/words_prefixes_fst.rs b/milli/src/update/words_prefixes_fst.rs
index 57fed0922..121b45c4a 100644
--- a/milli/src/update/words_prefixes_fst.rs
+++ b/milli/src/update/words_prefixes_fst.rs
@@ -42,6 +42,8 @@ impl<'t, 'u, 'i> WordsPrefixesFst<'t, 'u, 'i> {
 
     #[logging_timer::time("WordsPrefixesFst::{}")]
     pub fn execute(self) -> Result<()> {
+        puffin::profile_function!();
+
         let words_fst = self.index.words_fst(self.wtxn)?;
 
         let mut current_prefix = vec![SmallString32::new(); self.max_prefix_length];