What graphics card do you have? (I am guessing nvidia?)

On the p3 550mhz, i810. On the p4 3.06 ghz, yes, it is an nvidia (not legacy),
and I use the nvidia.com drivers. The model is NV17 [GeForce4 420 Go 64M]. I
dont think the video card is a problem, its works fine on ALL other browsers --
and I have tested every linux browser I know. 

Just there seems to be something in recent nivida drivers that works
super-duper-slow with the exact calls we and Qt use that other toolkits
don't... That didn't use to be the case with older drivers, so is really quite
a mess :-(. It may be worthwhile to try turning on RenderAccel.

Just to eliminate all possibilites, I used the free "nv" driver, turned off and
on RenderAccel, but in vain. Anything more for me to test ? :( I mean, hey,
i810 is beating an nvidia ;)

There is some problem here. The scrolling is pretty slow with me with an ati
graphics card and latest svn snapshot. Firefox scrolls fine

Works with i810 driver , Intel i915 card; slow with nvidia driver, NVIDIA GF
FX6200 card.

Related bug http://bugs.kde.org/show_bug.cgi?id=120805

Yeap, probably this bug is a duplicate

Also probably bug 52801 is related. Comment #5 there is very interesting

I dont think bug 52801 is related -- I dont use smooth scroll in either firefox
or konqueror. In fact, I use absolute plain defaults in konqueror, nothing
changed at all.

ATI Mobility Radeon X700: fast
I'll test an NVidia on Tuesday. For the moment, we're attributing this problem to the NVidia drivers.

can't reproduce. GeForce 6600 - Linux x86 NVIDIA Kernel Module  1.0-8178

>------- Additional Comment #12 From Germain Garand 2006-04-16 17:35 -------  
> can't reproduce. GeForce 6600 - Linux x86 NVIDIA Kernel Module  1.0-8178 
 
RenderAccel on/off ?

Tried with both. Firefox,opera is very fast, regardless whether it is on or no.
Turning it on improves the situation only *minimally* in konqui, its still
largely unusable.

re: #13 - off.
Fairly beefy machine though (X2 4600+)

Seems to be a slow RenderTableSection::paint()

Especially cellAt and operator[] on QMemArray.

Created an attachment (id=15660) [details]
Patch for speeding up RenderTableSection::paint()

Try this patch. It removes some stuff for drawing focus on table-rows, and
speeds up choice of rows to paint by using a binary-search.

Created an attachment (id=15663) [details]
Patch with better binary search

The last patch didn't do real binary search. I decided I might as well do it
right.

After patching scrolling on some pages ( like this bug report page ) results in
:

konqueror:
/home/cartman/KDE-SVN/KDE3/kdelibs/khtml/rendering/render_table.cpp:1595: void
findRowCover(unsigned int&, unsigned int&, const QMemArray<int>&, int, int):
Assertion `endrow == 0 || rowPos[endrow-1] < max_y' failed.
KCrash: Application 'konqueror' crashing...

I've commited my patch for binary lookup in painting. And while it speeds up
what little time Konqueror spends on painting a lot, 99% of the slowness turns
out to be from the x-server.

FYI, I experienced very low painting performances on some sites (e.g
http://fabula.org) with Mandriva 2006 on a XP 2400+ system /w nvidia 6600 gpu.
Supplied nvidia driver was 1.0.7676.

Installing latest updates solved the problem - among those were nvidia drivers
1.0.8756 (but also Xorg update to 6.9.0 final from some pre 6.9.0 snapshot, so
I can't conclusively point the finger at nvidia).

SVN commit 542397 by carewolf:

Only repaint the expossed area when scrolling. 
Fixing local mistakes makes our perfomance less dependent on fully optimized drivers.
BUG: 125580
BUG: 118806


 M  +9 -0      render_box.cpp  


--- branches/KDE/3.5/kdelibs/khtml/rendering/render_box.cpp #542396:542397
@@ -529,7 +529,16 @@
             sy+=b.y()-cy;
             cx=b.x();cy=b.y();cw=b.width();ch=b.height();
         }
+        // restrict painting to repaint-clip
+        if (cy < clipy) {
+            ch -= (clipy - cy);
+            sy += (clipy - cy);
+            cy = clipy;
+        }
+        ch = kMin(ch, cliph);
 
+// 	kdDebug() << " clipy, cliph: " << clipy << ", " << cliph << endl;
+//         kdDebug() << " drawTiledPixmap(" << cx << ", " << cy << ", " << cw << ", " << ch << ", " << sx << ", " << sy << ")" << endl;
         if (cw>0 && ch>0)
             p->drawTiledPixmap(cx, cy, cw, ch, bg->tiled_pixmap(c), sx, sy);