Re: Scrolling performance

[Michael Ekstrand <mekstran scl ameslab gov>]

On Jul 6, 2006, at 6:43 AM, Roo wrote:
> Welcome to the wonderful world of GTK... where performance keeps going
> down with every new version. My experience: GTK has always been a slug
> compared to other toolkits, but when I upgraded from FC4 to FC5, it
> included a version of GTK that was built with Cairo, and the 
> performance
> dropped even further. I can start Motif or Qt applications and they run
> fine -- they redraw quickly and generally perform well. GTK apps 
> though,
> particularly heavy text based ones... are pathetic. I wish I had a way 
> to
> capture both the look and feel of it and upload it somewhere just so I
> could publicly show just how bad the GTK developer have let things go. 
> I
> know that sounds trollish, but there really isn't any other way to
> describe it. It's awful.

Part of the problem/reason: for some reason, it seems to work (or at 
least give acceptable results) for many of us.  I've had no noticable 
problems on either my 2.66GHz P4, my 1.4 GHz Celeron, a 1.7 GHz Pentium 
M, or a dual-600MHz PIII (and GTK redrawing will only use one of those 
procs per app).  The P4 is with ATI's FireGL drivers, and the others 
with open-source drivers for either ATI or Intel chipsets.  I've also 
had quite acceptable performance on Windows on a variety of systems.  
The only systems I'm finding it slow on are Mac OS X.  And there, 
there's a significant difference between whether I'm using DarwinPorts 
or Fink.

So basically: there are more variables than just GTK.  And it's my 
guess (not documented or from anywhere but my head and the responses on 
this list! and I don't speak for any GTK devs) that on the GTK 
developers' systems, there really aren't any issues.  Fedora in general 
is horrendously slow - when I've had it installed, it's felt several 
times less responsive than Debian, Ubuntu, or Gentoo on the same 
system.  I don't know what Fedora does to busticate things, but they're 
probably doing something that has an adverse affect on performance 
outside those things in GTK proper (my first guess would be Bluecurve, 
but I really don't know).

That said, it is discouraging to see the lack of support for figuring 
out the problems where they do exist.  I can appreciate it some - 
people working on GTK probably have better things to do with their time 
than work around the ways Fedora and SuSE find to slow down the system. 
 But they're still issues.

Further, GTK seems to value correctness and straightforwardness over 
speed.  Not necessarily bad - computer time is cheaper than programmer 
time.  And it's had some great results.  GTK widgets are highly 
capable.  But I can see it getting slow.

> For what it's worth: I'm using a Matrox G550 with an open source driver
> (Direct rendering is enabled) on an Athlon XP 20000+. I dual boot with
> Windows XP, and rebooting the machine into Windows is a revelation. 
> Smooth
> and fast... same as the Qt/Motif apps. Someone should be ashamed of 
> that
> result, as if GTK didn't have a bad enough reputation for being poorly
> optimised already.

Do you have XComposite enabled?  The one or two times I've turned it 
on, it's been a sure-fire way to slow the entire system (although it 
slowed Qt apps too).

OK, so this has turned into a bit of a stream-of-conciousness message.  
But I hope it helps some...  and it most definitely is not intended as 
a flame, so please don't take it as one.

- Michael