[racket] big-bang is slow to render on screen?

Hello
on my laptop seem very fast
but Mint 16 (ubuntu 13.10) core i7/16Go
Racket 6.0.1.4--2014-04-18(ccefa53/a)
Cairo /usr/lib/i386-linux-gnu/libcairo.so.2.11200.16

to-draw at 334
to-draw: cpu time: 2 real time: 3 gc time: 0
on-key d at 442
to-draw at 442
to-draw: cpu time: 1 real time: 1 gc time: 0
to-draw at 532
to-draw: cpu time: 1 real time: 1 gc time: 0
on-key f at 633
to-draw at 633
to-draw: cpu time: 1 real time: 0 gc time: 0
to-draw at 728
to-draw: cpu time: 3 real time: 2 gc time: 0
on-key g at 828
to-draw at 829
to-draw: cpu time: 1 real time: 0 gc time: 0
to-draw at 919
to-draw: cpu time: 3 real time: 3 gc time: 0
on-key g at 995
to-draw at 996
to-draw: cpu time: 2 real time: 3 gc time: 0
to-draw at 1079
to-draw: cpu time: 1 real time: 1 gc time: 0

------------------------------------------------------------
Yvan Godin

120 rue de charonne    75011 PARIS
*tel: 06 18 82 28 60*
------------------------------------------------------------


2014-04-21 16:00 GMT+02:00 Laurent <laurent.orseau at gmail.com>:

> I have a 2htdp/universe program that used to run fast enough a few months
> ago, but now it is very slow and not usable.
> The slowness seems to be because of the on-screen rendering, and not
> because of the generation of the image.
>
> Here is a stripped-down version that shows this behavior:
> https://gist.github.com/Metaxal/11142941
>
> In the following log, you see that the `on-key` events are very close one
> to the other (in milliseconds after the beginning of the program), but the
> corresponding `to-draw` events are separated by more than a second, even
> though generating the image (cpu time) takes almost no time:
>
> on-key a at 6906
> on-key u at 6912
> on-key i at 6912
> on-key e at 6913
> to-draw at 6913
> to-draw: cpu time: 4 real time: 3 gc time: 0
> to-draw at 8598
> to-draw: cpu time: 4 real time: 2 gc time: 0
> to-draw at 11948
> to-draw: cpu time: 4 real time: 2 gc time: 0
> to-draw at 13631
> to-draw: cpu time: 0 real time: 2 gc time: 0
> to-draw at 161839
> to-draw: cpu time: 4 real time: 9 gc time: 0
>
> During those long seconds, Xorg is almost at 100% cpu.
>
> However, using an empty scene instead of an image is fast.
> The time also depends on the size of the grid.
>
> I'm using Ubuntu 12.04 64bits.
> I have tried to replicate the behavior on older versions of racket (5.3.1
> and 5.90.0.9) but it's the same. So maybe the problem is not on Racket's
> side but something has changed in Ubuntu?
>
> Does anyone else see the same behavior, either on the same platform or on
> a different one?
>
> Thanks,
> Laurent
>
>
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>   Racket Users list:
>   http://lists.racket-lang.org/users
>
>
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