Performance improvements for regex searching, most notably:

- Use the grid data directly instead of copying it.

- Special case the most typical one byte character cells and use memcmp
  for multiple bytes instead of a handrolled loop.

- Hoist regcomp out of the loop into the calling functions.

GitHub issue 2143.

Also a man page from from jmc@.

tmux.1

@@ -2312,7 +2312,8 @@ and unzoomed (its normal position in the layout).
 .Fl M
 begins mouse resizing (only valid if bound to a mouse key binding, see
 .Sx MOUSE SUPPORT ) .
-.Pp T
+.Pp
+.Fl T
 trims all lines below the current cursor position and moves lines out of the
 history to replace them.
 .It Xo Ic resize-window