[doveman2]

You'll get a better response by gathering more information.

visualizedirtyregions (http://wiki.xbmc.org/?title=advancedsettings.xml) should show you the "dirty" regions that are cauing the issue.
Normally that would just be animating/scrolling regions of the screen, but that bug is probably causing stationary parts of the screen to be considered dirty.

Use this in conjunction with:
<algorithmdirtyregions>1</algorithmdirtyregions>

and a nightly build (e.g. rbej's Gotham build) and investigate what parts of the screen are incorrectly marked as dirty.

I tried that but it makes the CPU run at 83%+ (with top) constantly, so it's pretty impossible to tell if anything's loading the CPU.

Anyway, most of the time when I'd expect to experience high CPU, there's no dirty regions showing, so that's obviously not the cause of it most of the time. The only one I did pick up is when going to the Recently Added movies at the top of the screen, moving onto one which starts the title scrolling, then moving to the right to next one, it leaves a dirty region square overlapping the edge of the two title boxes. Only scrolling the movies until these two go off the screen makes this square disappear, so that explains the problem I reported above.

A place where I see high CPU but not dirty regions is in Settings, when the right-hand pane is active. In the left-hand pane, the CPU is only 20% but as soon as I move to the right, it goes to 90% and stays there. With visualizedirtyregions on it was around 50-54% in either pane, so that obviously interferes with something.