Hi Juri,

I have attached a new patch addressing the issues we discussed.  I have
also changed the name of the new variable a bit, I hope it's a bit more
self-explanatory now.

I have also tested increasing ‘lazy-highlight-buffer-max-at-a-time’ to
1000.  I can't see any loss in responsiveness, except when the old value
of 20 also makes the editor freeze (for instance when searching for
".*a.*a$" in very large buffer).  This is probably a reasonable default.

Best,
Augusto