[FreeNX-kNX] NX performance issue

[DRC]

Hi there.  I develop an open source application (http://www.virtualgl.org)
which adds hardware-accelerated 3D capabilities to X proxies such as NX,
VNC, etc.  It works by rerouting the 3D rendering into a Pbuffer on the
server's graphics card, reading it back, and drawing it into the X proxy
using XShmPutImage() or using X pixmap drawing (if XShm isn't available.)

The essential workload that VirtualGL produces is a stream of full-screen
(usually 1280x1024), back-to-back calls to XShmPutImage() or XCopyArea(),
depending on whether the MIT-SHM extension is available.

And now, the issue -- in either case, what I observe with NX is that this
workload will perform great for about 3-5 seconds, then it will slow to a
crawl and remain slow.  I've tried various quality settings,
enabling/disabling the bitmap caches, etc., and nothing seems to improve the
situation.  Is there something else I could try?  Or is there perhaps a way
to profile that system and determine what's causing it to slow down?  I
don't observe this slow-down with other X servers (TurboVNC, specifically,
or even just sending the pixels via. remote X on a gigabit connection.)

Darrell Commander