This patch does the trick:

diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
index efe5210..68e490a 100644
--- a/Lib/test/libregrtest/refleak.py
+++ b/Lib/test/libregrtest/refleak.py
@@ -48,6 +48,11 @@ def dash_R(the_module, test, indirect_test, huntrleaks):
     print("beginning", repcount, "repetitions", file=sys.stderr)
     print(("1234567890"*(repcount//10 + 1))[:repcount], file=sys.stderr,
           flush=True)
+
+    int_pool = {i: i for i in range(-1000, 1000)}
+    def get_pooled_int(v):
+        return int_pool.setdefault(v, v)
+
     # initialize variables to make pyflakes quiet
     rc_before = alloc_before = fd_before = 0
     for i in range(repcount):
@@ -56,9 +61,9 @@ def dash_R(the_module, test, indirect_test, huntrleaks):
                                                          abcs)
         print('.', end='', file=sys.stderr, flush=True)
         if i >= nwarmup:
-            rc_deltas[i] = rc_after - rc_before
-            alloc_deltas[i] = alloc_after - alloc_before
-            fd_deltas[i] = fd_after - fd_before
+            rc_deltas[i] = get_pooled_int(rc_after - rc_before)
+            alloc_deltas[i] = get_pooled_int(alloc_after - alloc_before)
+            fd_deltas[i] = get_pooled_int(fd_after - fd_before)
         alloc_before = alloc_after
         rc_before = rc_after
         fd_before = fd_after