That is just a starting point of my optimization.
4.3.0-52 release should be more impressive :)
Takuma Murakami
> Takuma Murakami made an improvement to the multi-window code in the
> 4.3.0-51 release that restricts redraws to only the changed portions of
> windows. My earlier review of the original code made me believe that
> the code was redrawing the entire contents of each window, regardless of
> whether they had changed any or not, so I believe that Takuma's change
> is correct. In addition, I tested Takuma's change on a program that was
> notorious for exhibiting bad performance in multi-window mode: xfig.
> 4.3.0-50 requires 7 seconds to start xfig and there is lots of screen
> flashing during that startup process; other X Servers on Windows did not
> have this problem. 4.3.0-51 takes 2 seconds to start xfig and there is
> no longer any screen flashing.
>
> Takuma's changes are great! :)
>
> Harold