Re: emacs rendering comparisson between emacs23 and emacs26.3

[martin rudalics]

>> Or, alternatively, (setq fast-but-imprecise-scrolling t). This var seems
>> like a good idea in general, so we might consider going further with it.
>
> Try this:
>
> diff --git a/src/window.c b/src/window.c
> index 8cdad27b66..b23ae41aba 100644
> --- a/src/window.c
> +++ b/src/window.c
> @@ -5475,7 +5475,9 @@ window_scroll (Lisp_Object window, EMACS_INT n, bool 
whole, bool noerror)
>
>     wset_redisplay (XWINDOW (window));
>
> -  if (whole && Vfast_but_imprecise_scrolling)
> +  if (Vfast_but_imprecise_scrolling
> +      && (whole
> +          || EQ (Vthis_command, Qmwheel_scroll)))
>       specbind (Qfontification_functions, Qnil);
>
>     /* On GUI frames, use the pixel-based version which is much slower
> @@ -8173,6 +8175,7 @@ syms_of_window (void)
>     DEFSYM (Qmode_line_format, "mode-line-format");
>     DEFSYM (Qheader_line_format, "header-line-format");
>     DEFSYM (Qtab_line_format, "tab-line-format");
> +  DEFSYM (Qmwheel_scroll, "mwheel-scroll");
>
>     DEFVAR_LISP ("temp-buffer-show-function", Vtemp_buffer_show_function,
>           doc: /* Non-nil means call as function to display a help buffer.
>
>
> This eliminates all the delay I formerly saw while mouse scrolling as
> fast as possibly.

I tried that now and it makes no noticeable difference here.  Maybe I
did something wrong - all I checked via GDB was that it does perform the
specbinding.  Maybe that's not sufficient.

martin