Norihiro Tanaka wrote:
> Sorry, I forgot to send the patch.  We need the patch to optimize MERGE
> function to speed-up for some cases.

Thanks, that improved the performance of the 'grep -vf linux.words linux.words' 
benchmark from (before the recent changes) real 8.06 user 6.20 sys 1.85 to 
(after) real 2.57 user 2.11 sys 0.45.

I installed it (with minor tweaks to the ChangeLog) into gnulib master and 
updated the grep master accordingly. I'll CC: this email to bug-gnulib to give 
them a heads-up, attaching the revised patch.