Dear Maintainer,

This bug shows on my reasonably modern intel-powered laptop, on up-to-date
Debian12.

The obvious effect of the bug is that xdvi runs slowly, taking a perceptible
time to display a page.
As far as I can see xdvi (in fact xdvi-xaw which xdvi runs) uses XPutImage to
render text to the screen and XPutImage runs slowly.
  x11perf -putimage10 => 201000.0/sec
  x11perf -putimagexy10 => 6520.0/sec
This problem is similar to the one I found on much older hardware (see
Bug#1083049: xserver-xorg-core: Use of libglamor DECELERATES nouveau driver)
and again disabling the "glamor" acceleration extension is an
effective workaround.  I disabled glamor by making a file
  /etc/X11/xorg.conf.d/10-noGlamor.conf
with contents
--------snip-------------
Section "Device"
        Identifier "intelIrisXe"
        Driver "modesetting"
        Option "kmsdev" "/dev/dri/card0"
        Option "AccelMethod" "none" # "glamor"
EndSection
--------snip-------------

You can see from the log file that this successfully disables glamor.
After restarting X with glamor disabled, xdvi renders a page pretty much
instantly and
  x11perf -putimage10 => 1460000/sec  # was 201000/sec
  x11perf -putimagexy10  => 207000/sec # was 6520.0/sec

I thought before that this problem was to with the nouveau driver, but
that is not used on my laptop so it seems as if there is a more general
problem with libglamor or its use in the modesetting driver.

Although this bug is related to Bug#1083049 I thought it'd be better to file a
separate report because the title of the previous one makes the problem seem a
lot more niche than it evidently is.

Thanks for your attention.

John Payne