[Lazarus] IDE Editor incredibly slow on newer GTK2

[Martin]

On 24/03/2012 20:02, Bernd Kreuss wrote:
> I recently updated my ancient Ubuntu Hardy to Oneiric which has
> GTK-2.24.6. Now I noticed that the SynEdit in the Lazarus IDE feels
> painfully sluggish. If I press a key there is a 0.2 seconds delay until
> it updates the screen. If I keep the key pressed (auto-repeat) then xorg
> will burn 60% and kernel (IO or something) the remaining 40% of my CPU.
> It gets worse the bigger the editor window is (maximize window for
> maximum pain).
>
> Although one could argue that a Pentium-M (1 core at 1.3GHz) is not the
> fastest CPU I am not yet willing to throw away my good old thinkpad T40
> which has served me so well for such a long time.
>
> It does not happen if I use the Qt widgetset (but I rather do not want
> to use Qt but if this can't be fixed then I will have to, otherwise it
> is completely unusable, currently it feels like I'm sitting in front a
> 66MHz 386 from 1990).
>
> I can NOT reproduce it if I create a minimal application with a synedit
> and Pascal highlighter on it. I'm unable to reproduce this, no matter
> what options I set in my synedit or what highlighter I use and on the
>

Interesting.

This is without scrolling?

I would reckon that there is unnecessary painting going on (at least 
it's a possibility).  Any none painting code should be the same for QT, 
so ...

Compile the SynEdit package with the following defines
SynDebug
SynCaretDebug
SYNSCROLLDEBUG
VerboseSynEditInvalidate
SynCheckPaintLock

and get a logfile.

Please also try if switching the overview gutter (right hand site) 
(Options/Editor/Display) makes a different.  IIRC some WS does 
unnecessary invalidates (but not as bad as you described)

Or switch off highlight of all occurrences of the word under caret 
(obviously that can lead to a full invalidate, but usually it has a time 
delay, so it does not affect editing)