[squeak-dev] Why is the squeak gui slow? New clues.

Igor Stasenko siguctua at gmail.com
Tue Feb 16 19:09:31 UTC 2010

On 16 February 2010 20:38, Jerome Peace <peace_the_dreamer at yahoo.com> wrote:
> Most of the time squeak is fast enough. Every so often the gui slows down to a crawl. The user moves the mouse around and the gui will not respond the way it did a moment ago. Movements feel spastic. The user overshoots the mark, moves back, over shoots again. Gradually learning to pause ...a...long...time...between...very...small...movements.
> I was recently trying to program some improvements and did something I think sheds a light on the reason.
> I was fooling with the handles for a star morph. There are only 6 of them. Currently they all are individual submorphs of the star itself. However it seemed it would simplify things if there was only one handle. The center handle would make a good holder for the other five.
> When I finally got that working I ran into the problem that I mentioned in the first paragraph. The mouse gui became extremely retarded (in the time sense). This is consistent with what happens if you should run a mouse over true type fonts or flash morphs. The event processing slows down till it is painful to adjust to.
> My previous thought was that only massive pixel processing (large amount of screen updates) would cause a gui slowdown. Now however I am beginning to realize that event dispatch must be a prime suspect as well.
> That's all the info I have at the moment. I pass this along incase someone has some confirming or alternate information.

My 2 cents.
I played with morphic rendering code, where in my morph, all
attributes like color, border and many others retrieved from
I expected that it may cause a major slowdown, but then discovered
that its not. It is slower of course, but not to the point, where it
becomes noticeable. So, i suspecting that bottlenecks is hidden
somewhere else.

Another observation is, that if you open many windows, things become
slower and slower , in linear progression.
The fact is, that in browser windows, most time spent on rendering
text (using highly complex Text & font rendering code).
So, Text rendering is a major bottleneck. And if we want to make an
improvements, we should attack this area.

> Yours in curiosity and service, --Jerome Peace

Best regards,
Igor Stasenko AKA sig.

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