On 32-bit x86 (1.4Ghz Efficeon) using gcc 4.3.2-1ubuntu12 I see the 
following perf with pidigits_noprint 2000:

py3k:
baseline   longdigit14    longdigit13+optimizations
3709 ms    3664ms         4545ms

Those were from the best of five runs after a warmup loop while the 
system was idle.  --enable-big-digits was passed to configure and 
sys.int_info confirmed it was 30bits on the longdigit versions.

baseline is entirely unpatched.