diff --git a/runtime/src/accounts_db.rs b/runtime/src/accounts_db.rs
index db921b02dd8e02..66dd76f8a9a3a3 100644
--- a/runtime/src/accounts_db.rs
+++ b/runtime/src/accounts_db.rs
@@ -2448,9 +2448,10 @@ impl AccountsDb {
         });
         let dirty_stores_len = dirty_stores.len();
         let pubkeys = DashSet::new();
-        let mut dirty_store_routine = || {
+        let mut dirty_store_routine = |thread_count| {
+            let chunk_size = 1.max(dirty_stores_len.saturating_div(thread_count));
             let oldest_dirty_slots: Vec<u64> = dirty_stores
-                .par_chunks(4096)
+                .par_chunks(chunk_size)
                 .map(|dirty_store_chunk| {
                     let mut oldest_dirty_slot = max_slot.saturating_add(1);
                     dirty_store_chunk.iter().for_each(|(slot, store)| {
@@ -2469,9 +2470,11 @@ impl AccountsDb {
         };
 
         if is_startup {
-            dirty_store_routine();
+            dirty_store_routine(rayon::current_num_threads());
         } else {
-            self.thread_pool_clean.install(dirty_store_routine);
+            self.thread_pool_clean.install(|| {
+                dirty_store_routine(quarter_thread_count());
+            });
         }
         trace!(
             "dirty_stores.len: {} pubkeys.len: {}",