[jamesjones]

While the readbacks Aaron describes do cause considerable slowdown, there are many factors affecting window resizing with comosite managers, and especially window resizing with compiz. In particular, creating GLX drawables is a slow operation for various reasons. It is not a matter of simply allocating the memory. Compiz currently must create a GLX drawable for every "frame" of the resize operation. As mentioned, the X.Org developers are aware of the general problem, and we're also aware of the bottlenecks specific to our driver, and we're of course working on improvements as time permits. At this point, we're not blocked by lack of information from users on this one.