Attached are some proposed patches which should improve the performance 
of grep -P when applied to binary files, among other things.  I have 
some other ideas for boosting performance further but thought I'd 
publish these first.  Please give them a try if you have the time.  I 
doubt whether this will "solve" the performance problem entirely with -P 
and encoding errors but at least it should be heading in the right 
direction.