On Fri, Jan 3, 2014 at 6:21 AM, Andrea Rossetti <andrea.rossetti@gmail.com> wrote:
  Some more tests and your advice convinced me too
that DO is retaining some cells.

Andrea: I *think* you can explicitly call (gc)? If so, try something like this:

1. Turn on gcverbose.
2. Run a big do loop over i printing i. Invoke (gc) explicitly when i == 1, i == 2, and i = 100000

See if the retained heap space grows.

Kevin: if this reveals retention, I'm afraid I'm not likely to be able to debug the DO macro.