Brighten Godfrey wrote:
> That occurred to me too, but there is no swapping.  The process uses 
> less than 40 MB of memory.  Also, this wouldn't explain why it suddenly 
> becomes slow exactly when it starts parsing the file the second time.

This point is interesting: it is where PCRE starts compiling a lot of 
regexps while the OCaml heap is already full of non-garbage value (the 
value bound to first). For each allocated regexp, the OCaml PCRE binding 
pushes some pressure on the OCaml GC; maybe, then, the GC runs too often 
for the amount of memory it can really release.

-- Alain