RE: lax matching is not a great default behavior

[Drew Adams]

> > Seems to be lazy-highlight.  Set isearch-lazy-highlight to nil, and
> > Bob's your uncle.
> 
> If lazy-highlighting adds a lag before the user can move to the second
> match, then we need to fix lazy-highlighting to not block input.

Change the value of `laxy-highlight-max-at-a-time' to 1, to see no
blocking (no competition with reading input).  If you have it set
to, say, 20, then up to 20 isearch matches will be lazy-highlighted
before an already pressed additional `C-s' shows its effect by
moving to the next search hit.

This is very easy to see with symmetric folding turned on.  Lazy
highlighting occurs in bursts of `laxy-highlight-max-at-a-time'
search-occurrence highlights, and after each burst ordinary
search processing continues.