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 26ad68b71..cb1dcea51 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
@@ -1,5 +1,6 @@
 use std::fs::File;
 use std::io::{self, BufReader};
+use std::num::NonZeroUsize;
 
 use obkv::KvReaderU16;
 
@@ -9,8 +10,10 @@ use super::helpers::{
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
+use crate::update::del_add::{DelAdd, KvReaderDelAdd};
+use crate::update::index_documents::cache::SorterCacheDelAddCboRoaringBitmap;
 use crate::update::settings::InnerIndexSettingsDiff;
+use crate::update::MergeFn;
 use crate::Result;
 
 const MAX_COUNTED_WORDS: usize = 30;
@@ -26,10 +29,9 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
     indexer: GrenadParameters,
     _settings_diff: &InnerIndexSettingsDiff,
 ) -> Result<grenad::Reader<BufReader<File>>> {
-    let mut conn = super::REDIS_CLIENT.get_connection().unwrap();
     let max_memory = indexer.max_memory_by_thread();
 
-    let mut fid_word_count_docids_sorter = create_sorter(
+    let fid_word_count_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
         merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
@@ -37,9 +39,14 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
         indexer.max_nb_chunks,
         max_memory,
     );
+    let mut cached_fid_word_count_docids_sorter =
+        SorterCacheDelAddCboRoaringBitmap::<20, MergeFn>::new(
+            NonZeroUsize::new(300).unwrap(),
+            fid_word_count_docids_sorter,
+            super::REDIS_CLIENT.get_connection().unwrap(),
+        );
 
     let mut key_buffer = Vec::new();
-    let mut value_buffer = Vec::new();
     let mut cursor = docid_word_positions.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
         let (document_id_bytes, fid_bytes) = try_split_array_at(key)
@@ -65,30 +72,20 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
         if deletion != addition {
             // Insert deleted word count in sorter if exist.
             if let Some(word_count) = deletion {
-                value_buffer.clear();
-                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
-                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
                 key_buffer.clear();
                 key_buffer.extend_from_slice(fid_bytes);
                 key_buffer.push(word_count as u8);
-                redis::cmd("INCR").arg(key_buffer.as_slice()).query::<usize>(&mut conn).unwrap();
-                fid_word_count_docids_sorter
-                    .insert(&key_buffer, value_writer.into_inner().unwrap())?;
+                cached_fid_word_count_docids_sorter.insert_del_u32(&key_buffer, document_id)?;
             }
             // Insert added word count in sorter if exist.
             if let Some(word_count) = addition {
-                value_buffer.clear();
-                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
-                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
                 key_buffer.clear();
                 key_buffer.extend_from_slice(fid_bytes);
                 key_buffer.push(word_count as u8);
-                redis::cmd("INCR").arg(key_buffer.as_slice()).query::<usize>(&mut conn).unwrap();
-                fid_word_count_docids_sorter
-                    .insert(&key_buffer, value_writer.into_inner().unwrap())?;
+                cached_fid_word_count_docids_sorter.insert_add_u32(&key_buffer, document_id)?;
             }
         }
     }
 
-    sorter_into_reader(fid_word_count_docids_sorter, indexer)
+    sorter_into_reader(cached_fid_word_count_docids_sorter.into_sorter()?, indexer)
 }