diff --git a/Cargo.lock b/Cargo.lock
index 2ab2f706a..957dffbe4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1664,11 +1664,12 @@ checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 [[package]]
 name = "grenad"
 version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5232b2d157b7bf63d7abe1b12177039e58db2f29e377517c0cdee1578cca4c93"
+source = "git+https://github.com/meilisearch/grenad?branch=parallel-sorter#eafb6ae795af6078e087edf77e7cd31a26238707"
 dependencies = [
  "bytemuck",
  "byteorder",
+ "crossbeam-channel",
+ "rayon",
  "tempfile",
 ]
 
diff --git a/milli/Cargo.toml b/milli/Cargo.toml
index 68bc2d2b5..da259c65d 100644
--- a/milli/Cargo.toml
+++ b/milli/Cargo.toml
@@ -26,7 +26,8 @@ flatten-serde-json = { path = "../flatten-serde-json" }
 fst = "0.4.7"
 fxhash = "0.2.1"
 geoutils = "0.5.1"
-grenad = { version = "0.4.4", default-features = false, features = [
+grenad = { git = "https://github.com/meilisearch/grenad", branch = "parallel-sorter", default-features = false, features = [
+    "rayon",
     "tempfile",
 ] }
 heed = { git = "https://github.com/meilisearch/heed", tag = "v0.12.7", default-features = false, features = [
diff --git a/milli/src/update/index_documents/transform.rs b/milli/src/update/index_documents/transform.rs
index 23b5c78c1..8d1750c49 100644
--- a/milli/src/update/index_documents/transform.rs
+++ b/milli/src/update/index_documents/transform.rs
@@ -114,24 +114,43 @@ impl<'a, 'i> Transform<'a, 'i> {
         };
 
         // We initialize the sorter with the user indexing settings.
-        let original_sorter = create_sorter(
-            grenad::SortAlgorithm::Stable,
-            merge_function,
-            indexer_settings.chunk_compression_type,
-            indexer_settings.chunk_compression_level,
-            indexer_settings.max_nb_chunks,
-            indexer_settings.max_memory.map(|mem| mem / 2),
-        );
+        let original_sorter = {
+            let mut builder = grenad::Sorter::builder(merge_function);
+            builder.chunk_compression_type(indexer_settings.chunk_compression_type);
+            if let Some(level) = indexer_settings.chunk_compression_level {
+                builder.chunk_compression_level(level);
+            }
+            if let Some(nb_chunks) = indexer_settings.max_nb_chunks {
+                builder.max_nb_chunks(nb_chunks);
+            }
+            if let Some(memory) = indexer_settings.max_memory.map(|mem| mem / 2) {
+                builder.dump_threshold(memory);
+                builder.allow_realloc(false);
+            }
+            builder.sort_algorithm(grenad::SortAlgorithm::Stable);
+            builder.sort_in_parallel(true);
+            builder.build()
+        };
 
         // We initialize the sorter with the user indexing settings.
-        let flattened_sorter = create_sorter(
-            grenad::SortAlgorithm::Stable,
-            merge_function,
-            indexer_settings.chunk_compression_type,
-            indexer_settings.chunk_compression_level,
-            indexer_settings.max_nb_chunks,
-            indexer_settings.max_memory.map(|mem| mem / 2),
-        );
+        let flattened_sorter = {
+            let mut builder = grenad::Sorter::builder(merge_function);
+            builder.chunk_compression_type(indexer_settings.chunk_compression_type);
+            if let Some(level) = indexer_settings.chunk_compression_level {
+                builder.chunk_compression_level(level);
+            }
+            if let Some(nb_chunks) = indexer_settings.max_nb_chunks {
+                builder.max_nb_chunks(nb_chunks);
+            }
+            if let Some(memory) = indexer_settings.max_memory.map(|mem| mem / 2) {
+                builder.dump_threshold(memory);
+                builder.allow_realloc(false);
+            }
+            builder.sort_algorithm(grenad::SortAlgorithm::Stable);
+            builder.sort_in_parallel(true);
+            builder.build()
+        };
+
         let documents_ids = index.documents_ids(wtxn)?;
 
         Ok(Transform {