diff --git a/milli/src/update/new/extract/faceted/extract_facets.rs b/milli/src/update/new/extract/faceted/extract_facets.rs
index 9f3ed18d8..9fae1839e 100644
--- a/milli/src/update/new/extract/faceted/extract_facets.rs
+++ b/milli/src/update/new/extract/faceted/extract_facets.rs
@@ -54,12 +54,20 @@ impl<'extractor> Extractor<'extractor> for FacetedExtractorData<'extractor> {
         ))))
     }
 
-    fn process(
+    fn process<'doc>(
         &self,
-        change: DocumentChange,
-        context: &crate::update::new::indexer::document_changes::DocumentChangeContext<Self::Data>,
+        changes: impl Iterator<Item = Result<DocumentChange<'doc>>>,
+        context: &DocumentChangeContext<Self::Data>,
     ) -> Result<()> {
-        FacetedDocidsExtractor::extract_document_change(context, self.attributes_to_extract, change)
+        for change in changes {
+            let change = change?;
+            FacetedDocidsExtractor::extract_document_change(
+                context,
+                self.attributes_to_extract,
+                change,
+            )?
+        }
+        Ok(())
     }
 }
 
diff --git a/milli/src/update/new/extract/searchable/extract_word_docids.rs b/milli/src/update/new/extract/searchable/extract_word_docids.rs
index c76ab49d0..5eb9692d6 100644
--- a/milli/src/update/new/extract/searchable/extract_word_docids.rs
+++ b/milli/src/update/new/extract/searchable/extract_word_docids.rs
@@ -325,12 +325,16 @@ impl<'extractor> Extractor<'extractor> for WordDocidsExtractorData<'extractor> {
         ))))
     }
 
-    fn process(
+    fn process<'doc>(
         &self,
-        change: DocumentChange,
-        context: &crate::update::new::indexer::document_changes::DocumentChangeContext<Self::Data>,
+        changes: impl Iterator<Item = Result<DocumentChange<'doc>>>,
+        context: &DocumentChangeContext<Self::Data>,
     ) -> Result<()> {
-        WordDocidsExtractors::extract_document_change(context, self.tokenizer, change)
+        for change in changes {
+            let change = change?;
+            WordDocidsExtractors::extract_document_change(context, self.tokenizer, change)?;
+        }
+        Ok(())
     }
 }
 
diff --git a/milli/src/update/new/extract/searchable/mod.rs b/milli/src/update/new/extract/searchable/mod.rs
index 8934ee892..dc429b1ba 100644
--- a/milli/src/update/new/extract/searchable/mod.rs
+++ b/milli/src/update/new/extract/searchable/mod.rs
@@ -55,12 +55,16 @@ impl<'extractor, EX: SearchableExtractor + Sync> Extractor<'extractor>
         ))))
     }
 
-    fn process(
+    fn process<'doc>(
         &self,
-        change: DocumentChange,
-        context: &crate::update::new::indexer::document_changes::DocumentChangeContext<Self::Data>,
+        changes: impl Iterator<Item = Result<DocumentChange<'doc>>>,
+        context: &DocumentChangeContext<Self::Data>,
     ) -> Result<()> {
-        EX::extract_document_change(context, self.tokenizer, change)
+        for change in changes {
+            let change = change?;
+            EX::extract_document_change(context, self.tokenizer, change)?;
+        }
+        Ok(())
     }
 }
 
diff --git a/milli/src/update/new/indexer/document_changes.rs b/milli/src/update/new/indexer/document_changes.rs
index 423ddbdcc..91c65a6d1 100644
--- a/milli/src/update/new/indexer/document_changes.rs
+++ b/milli/src/update/new/indexer/document_changes.rs
@@ -323,7 +323,7 @@ pub trait Extractor<'extractor>: Sync {
 
     fn process<'doc>(
         &'doc self,
-        change: DocumentChange<'doc>,
+        changes: impl Iterator<Item = Result<DocumentChange<'doc>>>,
         context: &'doc DocumentChangeContext<Self::Data>,
     ) -> Result<()>;
 }
@@ -332,13 +332,13 @@ pub trait DocumentChanges<'pl // lifetime of the underlying payload
 >: Sync {
     type Item: Send;
 
-    fn iter(&self) -> impl IndexedParallelIterator<Item = Self::Item>;
+    fn iter(&self, chunk_size: usize) -> impl IndexedParallelIterator<Item = impl AsRef<[Self::Item]>>;
 
     fn item_to_document_change<'doc, // lifetime of a single `process` call
      T: MostlySend>(
         &'doc self,
         context: &'doc DocumentChangeContext<T>,
-        item: Self::Item,
+        item: &'doc Self::Item,
     ) -> Result<Option<DocumentChange<'doc>>> where 'pl: 'doc // the payload must survive the process calls
     ;
 }
@@ -356,6 +356,8 @@ pub struct IndexingContext<
     pub fields_ids_map_store: &'indexer ThreadLocal<FullySend<RefCell<GlobalFieldsIdsMap<'fid>>>>,
 }
 
+const CHUNK_SIZE: usize = 100;
+
 pub fn for_each_document_change<
     'pl,        // covariant lifetime of the underlying payload
     'extractor, // invariant lifetime of extractor_alloc
@@ -386,7 +388,7 @@ where
         extractor_alloc.0.get_mut().reset();
     }
 
-    let pi = document_changes.iter();
+    let pi = document_changes.iter(CHUNK_SIZE);
     pi.try_arc_for_each_try_init(
         || {
             DocumentChangeContext::new(
@@ -400,17 +402,16 @@ where
                 move |index_alloc| extractor.init_data(index_alloc),
             )
         },
-        |context, item| {
+        |context, items| {
             // Clean up and reuse the document-specific allocator
             context.doc_alloc.reset();
 
-            let Some(change) =
-                document_changes.item_to_document_change(context, item).map_err(Arc::new)?
-            else {
-                return Ok(());
-            };
+            let items = items.as_ref();
+            let changes = items.iter().filter_map(|item| {
+                document_changes.item_to_document_change(context, item).transpose()
+            });
 
-            let res = extractor.process(change, context).map_err(Arc::new);
+            let res = extractor.process(changes, context).map_err(Arc::new);
 
             // send back the doc_alloc in the pool
             context.doc_allocs.get_or_default().0.set(std::mem::take(&mut context.doc_alloc));
diff --git a/milli/src/update/new/indexer/document_deletion.rs b/milli/src/update/new/indexer/document_deletion.rs
index a9628f419..bbd2b11ac 100644
--- a/milli/src/update/new/indexer/document_deletion.rs
+++ b/milli/src/update/new/indexer/document_deletion.rs
@@ -1,6 +1,7 @@
 use bumpalo::collections::CollectIn;
 use bumpalo::Bump;
-use rayon::iter::{IntoParallelIterator, ParallelIterator as _};
+use rayon::iter::IndexedParallelIterator;
+use rayon::slice::ParallelSlice as _;
 use roaring::RoaringBitmap;
 
 use super::document_changes::{DocumentChangeContext, DocumentChanges, MostlySend};
@@ -44,8 +45,11 @@ pub struct DocumentDeletionChanges<'indexer> {
 impl<'pl> DocumentChanges<'pl> for DocumentDeletionChanges<'pl> {
     type Item = DocumentId;
 
-    fn iter(&self) -> impl rayon::prelude::IndexedParallelIterator<Item = Self::Item> {
-        self.to_delete.into_par_iter().copied()
+    fn iter(
+        &self,
+        chunk_size: usize,
+    ) -> impl IndexedParallelIterator<Item = impl AsRef<[Self::Item]>> {
+        self.to_delete.par_chunks(chunk_size)
     }
 
     fn item_to_document_change<
@@ -54,12 +58,12 @@ impl<'pl> DocumentChanges<'pl> for DocumentDeletionChanges<'pl> {
     >(
         &'doc self,
         context: &'doc DocumentChangeContext<T>,
-        docid: Self::Item,
+        docid: &'doc Self::Item,
     ) -> Result<Option<DocumentChange<'doc>>>
     where
         'pl: 'doc, // the payload must survive the process calls
     {
-        let current = context.index.document(&context.txn, docid)?;
+        let current = context.index.document(&context.txn, *docid)?;
 
         let external_document_id = self.primary_key.extract_docid_from_db(
             current,
@@ -69,7 +73,7 @@ impl<'pl> DocumentChanges<'pl> for DocumentDeletionChanges<'pl> {
 
         let external_document_id = external_document_id.to_bump(&context.doc_alloc);
 
-        Ok(Some(DocumentChange::Deletion(Deletion::create(docid, external_document_id))))
+        Ok(Some(DocumentChange::Deletion(Deletion::create(*docid, external_document_id))))
     }
 }
 
@@ -118,12 +122,15 @@ mod test {
                 Ok(DeletionWithData { deleted })
             }
 
-            fn process(
+            fn process<'doc>(
                 &self,
-                change: DocumentChange,
+                changes: impl Iterator<Item = crate::Result<DocumentChange<'doc>>>,
                 context: &DocumentChangeContext<Self::Data>,
             ) -> crate::Result<()> {
-                context.data.deleted.borrow_mut().insert(change.docid());
+                for change in changes {
+                    let change = change?;
+                    context.data.deleted.borrow_mut().insert(change.docid());
+                }
                 Ok(())
             }
         }
diff --git a/milli/src/update/new/indexer/document_operation.rs b/milli/src/update/new/indexer/document_operation.rs
index 57ec46a41..ee4517e20 100644
--- a/milli/src/update/new/indexer/document_operation.rs
+++ b/milli/src/update/new/indexer/document_operation.rs
@@ -3,6 +3,7 @@ use bumpalo::Bump;
 use heed::RoTxn;
 use memmap2::Mmap;
 use rayon::iter::IntoParallelIterator;
+use rayon::slice::ParallelSlice;
 use serde_json::value::RawValue;
 use IndexDocumentsMethod as Idm;
 
@@ -209,16 +210,19 @@ impl<'pl> DocumentOperation<'pl> {
 }
 
 impl<'pl> DocumentChanges<'pl> for DocumentOperationChanges<'pl> {
-    type Item = &'pl (&'pl str, ((u32, bool), &'pl [InnerDocOp<'pl>]));
+    type Item = (&'pl str, ((u32, bool), &'pl [InnerDocOp<'pl>]));
 
-    fn iter(&self) -> impl rayon::prelude::IndexedParallelIterator<Item = Self::Item> {
-        self.docids_version_offsets.into_par_iter()
+    fn iter(
+        &self,
+        chunk_size: usize,
+    ) -> impl rayon::prelude::IndexedParallelIterator<Item = impl AsRef<[Self::Item]>> {
+        self.docids_version_offsets.par_chunks(chunk_size)
     }
 
     fn item_to_document_change<'doc, T: MostlySend + 'doc>(
         &'doc self,
         context: &'doc DocumentChangeContext<T>,
-        item: Self::Item,
+        item: &'doc Self::Item,
     ) -> Result<Option<DocumentChange<'doc>>>
     where
         'pl: 'doc,
diff --git a/milli/src/update/new/indexer/mod.rs b/milli/src/update/new/indexer/mod.rs
index 29ff2685e..d4e6ca6a6 100644
--- a/milli/src/update/new/indexer/mod.rs
+++ b/milli/src/update/new/indexer/mod.rs
@@ -5,8 +5,8 @@ use std::thread::{self, Builder};
 use big_s::S;
 use bumpalo::Bump;
 use document_changes::{
-    for_each_document_change, DocumentChanges, Extractor, FullySend, IndexingContext, RefCellExt,
-    ThreadLocal,
+    for_each_document_change, DocumentChangeContext, DocumentChanges, Extractor, FullySend,
+    IndexingContext, RefCellExt, ThreadLocal,
 };
 pub use document_deletion::DocumentDeletion;
 pub use document_operation::DocumentOperation;
@@ -33,7 +33,7 @@ use crate::update::new::channel::ExtractorSender;
 use crate::update::new::words_prefix_docids::compute_exact_word_prefix_docids;
 use crate::update::settings::InnerIndexSettings;
 use crate::update::{FacetsUpdateBulk, GrenadParameters};
-use crate::{Error, FieldsIdsMap, GlobalFieldsIdsMap, Index, Result, UserError};
+use crate::{FieldsIdsMap, GlobalFieldsIdsMap, Index, Result, UserError};
 
 pub(crate) mod de;
 pub mod document_changes;
@@ -56,10 +56,10 @@ impl<'a, 'extractor> Extractor<'extractor> for DocumentExtractor<'a> {
         Ok(FullySend(()))
     }
 
-    fn process(
+    fn process<'doc>(
         &self,
-        change: DocumentChange,
-        context: &document_changes::DocumentChangeContext<Self::Data>,
+        changes: impl Iterator<Item = Result<DocumentChange<'doc>>>,
+        context: &DocumentChangeContext<Self::Data>,
     ) -> Result<()> {
         let mut document_buffer = Vec::new();
 
@@ -67,32 +67,36 @@ impl<'a, 'extractor> Extractor<'extractor> for DocumentExtractor<'a> {
         let new_fields_ids_map = &*new_fields_ids_map;
         let new_fields_ids_map = new_fields_ids_map.local_map();
 
-        let external_docid = change.external_docid().to_owned();
+        for change in changes {
+            let change = change?;
+            let external_docid = change.external_docid().to_owned();
 
-        // document but we need to create a function that collects and compresses documents.
-        match change {
-            DocumentChange::Deletion(deletion) => {
-                let docid = deletion.docid();
-                self.document_sender.delete(docid, external_docid).unwrap();
-            }
-            /// TODO: change NONE by SOME(vector) when implemented
-            DocumentChange::Update(update) => {
-                let docid = update.docid();
-                let content =
-                    update.new(&context.txn, context.index, &context.db_fields_ids_map)?;
-                let content =
-                    write_to_obkv(&content, None, new_fields_ids_map, &mut document_buffer)?;
-                self.document_sender.insert(docid, external_docid, content.boxed()).unwrap();
-            }
-            DocumentChange::Insertion(insertion) => {
-                let docid = insertion.docid();
-                let content = insertion.new();
-                let content =
-                    write_to_obkv(&content, None, new_fields_ids_map, &mut document_buffer)?;
-                self.document_sender.insert(docid, external_docid, content.boxed()).unwrap();
-                // extracted_dictionary_sender.send(self, dictionary: &[u8]);
+            // document but we need to create a function that collects and compresses documents.
+            match change {
+                DocumentChange::Deletion(deletion) => {
+                    let docid = deletion.docid();
+                    self.document_sender.delete(docid, external_docid).unwrap();
+                }
+                /// TODO: change NONE by SOME(vector) when implemented
+                DocumentChange::Update(update) => {
+                    let docid = update.docid();
+                    let content =
+                        update.new(&context.txn, context.index, &context.db_fields_ids_map)?;
+                    let content =
+                        write_to_obkv(&content, None, new_fields_ids_map, &mut document_buffer)?;
+                    self.document_sender.insert(docid, external_docid, content.boxed()).unwrap();
+                }
+                DocumentChange::Insertion(insertion) => {
+                    let docid = insertion.docid();
+                    let content = insertion.new();
+                    let content =
+                        write_to_obkv(&content, None, new_fields_ids_map, &mut document_buffer)?;
+                    self.document_sender.insert(docid, external_docid, content.boxed()).unwrap();
+                    // extracted_dictionary_sender.send(self, dictionary: &[u8]);
+                }
             }
         }
+
         Ok(())
     }
 }
diff --git a/milli/src/update/new/indexer/partial_dump.rs b/milli/src/update/new/indexer/partial_dump.rs
index 10fc95a03..470dbc9d5 100644
--- a/milli/src/update/new/indexer/partial_dump.rs
+++ b/milli/src/update/new/indexer/partial_dump.rs
@@ -45,14 +45,17 @@ where
 {
     type Item = Box<RawValue>;
 
-    fn iter(&self) -> impl IndexedParallelIterator<Item = Self::Item> {
-        self.iter.clone()
+    fn iter(
+        &self,
+        chunk_size: usize,
+    ) -> impl IndexedParallelIterator<Item = impl AsRef<[Self::Item]>> {
+        self.iter.clone().chunks(chunk_size)
     }
 
     fn item_to_document_change<'doc, T: MostlySend + 'doc>(
         &'doc self,
         context: &'doc DocumentChangeContext<T>,
-        document: Self::Item,
+        document: &'doc Self::Item,
     ) -> Result<Option<DocumentChange<'doc>>>
     where
         'index: 'doc,
diff --git a/milli/src/update/new/indexer/update_by_function.rs b/milli/src/update/new/indexer/update_by_function.rs
index 826f918a4..4c65edcc3 100644
--- a/milli/src/update/new/indexer/update_by_function.rs
+++ b/milli/src/update/new/indexer/update_by_function.rs
@@ -1,7 +1,6 @@
-use std::collections::BTreeMap;
-
 use raw_collections::RawMap;
-use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
+use rayon::iter::IndexedParallelIterator;
+use rayon::slice::ParallelSlice as _;
 use rhai::{Dynamic, Engine, OptimizationLevel, Scope, AST};
 use roaring::RoaringBitmap;
 
@@ -12,8 +11,8 @@ use crate::documents::PrimaryKey;
 use crate::error::{FieldIdMapMissingEntry, InternalError};
 use crate::update::new::document::DocumentFromVersions;
 use crate::update::new::document_change::Versions;
-use crate::update::new::{Deletion, DocumentChange, KvReaderFieldId, KvWriterFieldId, Update};
-use crate::{all_obkv_to_json, Error, FieldsIdsMap, GlobalFieldsIdsMap, Object, Result, UserError};
+use crate::update::new::{Deletion, DocumentChange, KvReaderFieldId, Update};
+use crate::{all_obkv_to_json, Error, FieldsIdsMap, Object, Result, UserError};
 
 pub struct UpdateByFunction {
     documents: RoaringBitmap,
@@ -76,14 +75,17 @@ impl UpdateByFunction {
 impl<'index> DocumentChanges<'index> for UpdateByFunctionChanges<'index> {
     type Item = u32;
 
-    fn iter(&self) -> impl IndexedParallelIterator<Item = Self::Item> {
-        self.documents.par_iter().copied()
+    fn iter(
+        &self,
+        chunk_size: usize,
+    ) -> impl IndexedParallelIterator<Item = impl AsRef<[Self::Item]>> {
+        self.documents.as_slice().par_chunks(chunk_size)
     }
 
     fn item_to_document_change<'doc, T: MostlySend + 'doc>(
         &self,
         context: &'doc DocumentChangeContext<T>,
-        docid: Self::Item,
+        docid: &'doc Self::Item,
     ) -> Result<Option<DocumentChange<'doc>>>
     where
         'index: 'doc,
@@ -97,6 +99,8 @@ impl<'index> DocumentChanges<'index> for UpdateByFunctionChanges<'index> {
             ..
         } = context;
 
+        let docid = *docid;
+
         // safety: Both documents *must* exists in the database as
         //         their IDs comes from the list of documents ids.
         let document = index.document(txn, docid)?;