diff --git a/runtime/src/bucket_map_holder_stats.rs b/runtime/src/bucket_map_holder_stats.rs
index 69cbd1460e..663180124d 100644
--- a/runtime/src/bucket_map_holder_stats.rs
+++ b/runtime/src/bucket_map_holder_stats.rs
@@ -43,7 +43,8 @@ pub struct BucketMapHolderStats {
     pub get_range_us: AtomicU64,
     last_age: AtomicU8,
     last_ages_flushed: AtomicU64,
-    pub flush_scan_update_us: AtomicU64,
+    pub flush_scan_us: AtomicU64,
+    pub flush_update_us: AtomicU64,
     pub flush_remove_us: AtomicU64,
     pub flush_grow_us: AtomicU64,
     last_was_startup: AtomicBool,
@@ -329,8 +330,13 @@ impl BucketMapHolderStats {
                 ("keys", self.keys.swap(0, Ordering::Relaxed), i64),
                 ("ms_per_age", ms_per_age, i64),
                 (
-                    "flush_scan_update_us",
-                    self.flush_scan_update_us.swap(0, Ordering::Relaxed),
+                    "flush_scan_us",
+                    self.flush_scan_us.swap(0, Ordering::Relaxed),
+                    i64
+                ),
+                (
+                    "flush_update_us",
+                    self.flush_update_us.swap(0, Ordering::Relaxed),
                     i64
                 ),
                 (
diff --git a/runtime/src/in_mem_accounts_index.rs b/runtime/src/in_mem_accounts_index.rs
index efd6b4cf5f..3dfdd585cc 100644
--- a/runtime/src/in_mem_accounts_index.rs
+++ b/runtime/src/in_mem_accounts_index.rs
@@ -948,20 +948,21 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
             .store(estimate_mem as u64, Ordering::Relaxed);
 
         // may have to loop if disk has to grow and we have to restart
-        loop {
+        {
+            let mut dirty_items;
             let mut evictions;
             let mut evictions_random = Vec::default();
             let disk = self.bucket.as_ref().unwrap();
 
             let mut flush_entries_updated_on_disk = 0;
-            let mut disk_resize = Ok(());
             let mut flush_should_evict_us = 0;
-            // scan and update loop
+            // scan loop
             // holds read lock
             {
                 let map = self.map().read().unwrap();
                 evictions = Vec::with_capacity(map.len());
-                let m = Measure::start("flush_scan_and_update"); // we don't care about lock time in this metric - bg threads can wait
+                dirty_items = Vec::with_capacity(map.len());
+                let m = Measure::start("flush_scan"); // we don't care about lock time in this metric - bg threads can wait
                 for (k, v) in map.iter() {
                     let mut mse = Measure::start("flush_should_evict");
                     let (evict_for_age, slot_list) =
@@ -982,18 +983,7 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
                         //  That prevents dropping an item from cache before disk is updated to latest in mem.
                         // happens inside of lock on in-mem cache. This is because of deleting items
                         // it is possible that the item in the cache is marked as dirty while these updates are happening. That is ok.
-                        {
-                            let slot_list =
-                                slot_list.unwrap_or_else(|| v.slot_list.read().unwrap());
-                            disk_resize = disk.try_write(k, (&slot_list, v.ref_count()));
-                        }
-                        if disk_resize.is_ok() {
-                            flush_entries_updated_on_disk += 1;
-                        } else {
-                            // disk needs to resize, so mark all unprocessed items as dirty again so we pick them up after the resize
-                            v.set_dirty(true);
-                            break;
-                        }
+                        dirty_items.push((*k, Arc::clone(v)));
                     } else {
                         drop(slot_list);
                     }
@@ -1003,7 +993,36 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
                         evictions_random.push(*k);
                     }
                 }
-                Self::update_time_stat(&self.stats().flush_scan_update_us, m);
+                Self::update_time_stat(&self.stats().flush_scan_us, m);
+            }
+            {
+                // write to disk outside giant read lock
+                let m = Measure::start("flush_update"); // we don't care about lock time in this metric - bg threads can wait
+                for (k, v) in dirty_items {
+                    if v.dirty() {
+                        // already marked dirty again, skip it
+                        continue;
+                    }
+                    loop {
+                        let disk_resize = {
+                            let slot_list = v.slot_list.read().unwrap();
+                            disk.try_write(&k, (&slot_list, v.ref_count()))
+                        };
+                        match disk_resize {
+                            Ok(_) => {
+                                // successfully written to disk
+                                flush_entries_updated_on_disk += 1;
+                            }
+                            Err(err) => {
+                                // disk needs to resize. This item did not get resized. Resize and try again.
+                                let m = Measure::start("flush_grow");
+                                disk.grow(err);
+                                Self::update_time_stat(&self.stats().flush_grow_us, m);
+                            }
+                        }
+                    }
+                }
+                Self::update_time_stat(&self.stats().flush_update_us, m);
             }
             Self::update_stat(&self.stats().flush_should_evict_us, flush_should_evict_us);
 
@@ -1012,29 +1031,18 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
                 flush_entries_updated_on_disk,
             );
 
-            let m = Measure::start("flush_evict_or_grow");
-            match disk_resize {
-                Ok(_) => {
-                    if !self.evict_from_cache(evictions, current_age, startup, false)
-                        || !self.evict_from_cache(evictions_random, current_age, startup, true)
-                    {
-                        iterate_for_age = false; // did not make it all the way through this bucket, so didn't handle age completely
-                    }
-                    Self::update_time_stat(&self.stats().flush_remove_us, m);
+            let m = Measure::start("flush_evict");
+            if !self.evict_from_cache(evictions, current_age, startup, false)
+                || !self.evict_from_cache(evictions_random, current_age, startup, true)
+            {
+                iterate_for_age = false; // did not make it all the way through this bucket, so didn't handle age completely
+            }
+            Self::update_time_stat(&self.stats().flush_remove_us, m);
 
-                    if iterate_for_age {
-                        // completed iteration of the buckets at the current age
-                        assert_eq!(current_age, self.storage.current_age());
-                        self.set_has_aged(current_age);
-                    }
-                    return;
-                }
-                Err(err) => {
-                    // grow the bucket, outside of all in-mem locks.
-                    // then, loop to try again
-                    disk.grow(err);
-                    Self::update_time_stat(&self.stats().flush_grow_us, m);
-                }
+            if iterate_for_age {
+                // completed iteration of the buckets at the current age
+                assert_eq!(current_age, self.storage.current_age());
+                self.set_has_aged(current_age);
             }
         }
     }