GtkTextView : crazy scrolling for cpu slowness ?!!?

[lorenzo zampese electrolux it]

I have got a Linux Red Hat 8.0, Amd K6-2 500Mhz cpu,
256 MB of ram, the windows manger is WindowMaker,
Gtk is version 2.

Follows my question :

I load a long text (1000 lines) in a TextView widget and when I press and
HOLD DOWN
the Page Up or Page Down buttons for scrolling text, I cannot watch a
correct
scrolling but it seems to me the widget makes a sort of "loop scrolling"
...

While if press page up/down WITHOUT holding down buttons the scrolling is
perfect !

I haven't got the "loop scrolling" problem in the same application compiled
and used under Windows 2000 with a Pentium 3 1000Mhz class cpu with 128MB
of ram....

Does the "loop scrolling" depend on a cpu slowness under linux or what ?
Any idea ?

Thank you :)