Eric on Wednesday posted a set of 19 new patches for cleaning up GLAMOR as he's working towards better performance. He explained at the start of the patch series, "I've been working on vc4 X performance again, particularly looking at dragging windows with xcompmgr -c running. I'll be sending a separate patch to accelerate a8 rendering on GLES2-class renderers, but even with that things are crazy slow. I think at this point the major problem is the crazy mass of code from rel_sampler(). This series was some cleanups as I worked toward that, and finally one patch that should reduce the cost of rel_sampler on non-control-flow hardware (I see fewer texture sampler requests on vc4). No performance change on i965, but I hope that vc4 is in better shape after it."
This work -- and hopefully more improvements for GLAMOR -- will be part of the X.Org Server 1.19 release due out later this year.