diff --git a/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/imputation.py b/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/imputation.py
index 38a6747..08a0c98 100644
--- a/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/imputation.py
+++ b/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/imputation.py
@@ -336,7 +336,7 @@ async def impute(args: dict):
                                                 batch_regions,
                                                 args['use_checkpoints'],
                                                 contig,
-                                                len(chunks))
+                                                len(chunks) * 5)
 
         if union_j is not None:
             union_j.depends_on(*union_ligate_input_jobs.get(contig, []))
diff --git a/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/jobs.py b/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/jobs.py
index 666777c..eeb4943 100644
--- a/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/jobs.py
+++ b/imputation/glimpse_hail_batch/glimpse_hail_batch/imputation/jobs.py
@@ -489,6 +489,8 @@ def add_info_if_needed(mt):
     mt_init = hl.read_matrix_table(paths[0])
     intervals = mt_init._calculate_new_partitions(n_partitions)
 
+    last_mt_left = None
+
     mt_left = hl.read_matrix_table(paths[0], _intervals=intervals)
     mt_left = add_info_if_needed(mt_left)
     mt_left = mt_left.annotate_rows(
@@ -510,6 +512,12 @@ def add_info_if_needed(mt):
                                      drop_right_row_fields=False,
                                      row_join_type='outer')
 
+        if idx % 5 == 0:
+            mt_left = mt_left.persist()
+            if last_mt_left is not None:
+                last_mt_left.unpersist()
+            last_mt_left = mt_left
+
     mt = mt_left
 
     n_batches = len(paths)