diff --git a/mps/manual/source/guide/debug.rst b/mps/manual/source/guide/debug.rst
index daf3fb63ae5..ddc46244c09 100644
--- a/mps/manual/source/guide/debug.rst
+++ b/mps/manual/source/guide/debug.rst
@@ -66,7 +66,10 @@ General debugging advice
    result, by having a mode for testing in which you run frequent
    collections (by calling :c:func:`mps_arena_collect` followed by
    :c:func:`mps_arena_release`), perhaps as frequently as every
-   allocation.
+   allocation. (This will of course make the system run very slowly,
+   but it ensures that if there are roots or references that are not
+   being scanned then the failure will occur close in time to the cause,
+   making it easier to diagnose.)
 
 #. .. index::
       single: debugger