Re: Fwd: Serious performace problems on Windows XP with new(!) GNU Emacs v22 (both patched and unpatched EmacsW32 were tried)

[martin rudalics]

> I tried M-: (remove-overlays nil nil 'face 'whitespace-highlight) and
> it took about the same time what was the increment between first and
> other runs. Evaluating it when point is at bottom, very fast, but when
> point is at top, it is slow.
>
> I think you can easily test it by making slowtst.el a few times bigger
> and then measuring the run times.

I see.  Please replace the two lines

          (remove-overlays nil nil 'face 'whitespace-highlight)
          (overlay-recenter (point-max))

by

          (overlay-recenter (point-max))
          (dolist (overlay (overlays-in (point-min) (point-max)))
            (when (eq (overlay-get overlay 'face) 'whitespace-highlight)
              (delete-overlay overlay)))

and tell me whether this improves things for your problematic file.