diff --git a/packages/ludic.base/ecs_index_slot.ludic b/packages/ludic.base/ecs_index_slot.ludic
index e35155c9..c4c2a4a5 100644
--- a/packages/ludic.base/ecs_index_slot.ludic
+++ b/packages/ludic.base/ecs_index_slot.ludic
@@ -2,6 +2,13 @@
 # slot; a large one (a chunk's packed cell) is given the next slot through a map, so a sparse
 # value costs one list and not every list up to it
 const IX_DENSE: int = 1024     # a value below this is its own slot; above, one is given it
+const IX_CAP: int = 16         # rows a value's list holds before it grows: a list grown in play is a new block
+
+function ix_list_new() -> words {
+  let l = words(IX_CAP)
+  List.clear(l)
+  return l
+}
 
 # the slot value v's list is in, -1 when it has none (and `make` did not ask for one)
 function ix_slot(ix: IntIndex, v: int, make: bool) -> int {
@@ -9,15 +16,15 @@ function ix_slot(ix: IntIndex, v: int, make: bool) -> int {
   if v < IX_DENSE {
     if v >= len(ix.lists) {
       if not make { return -1 }
-      while len(ix.lists) <= v { push(ix.lists, words(0)) }
+      while len(ix.lists) <= v { push(ix.lists, ix_list_new()) }
     }
     return v
   }
   var s = imap_get(ix.sparse, v, -1)
   if s < 0 and make {
-    while len(ix.lists) < IX_DENSE { push(ix.lists, words(0)) }
+    while len(ix.lists) < IX_DENSE { push(ix.lists, ix_list_new()) }
     s = len(ix.lists)
-    push(ix.lists, words(0))
+    push(ix.lists, ix_list_new())
     imap_put(ix.sparse, v, s)
   }
   return s