Comment 5 for bug 1025586

I did notice just now that we're probably calling through to sendConfigureNotify a lot more often than we are normally now, which involves a lot of X11 pipeline flushing (eg, have to call XSync to get the server side positions etc). It is probably safe to call sendConfigureNotify to update clients as to their position when we receive the new position from the server.

It doesn't exactly explain why we're slow on llvmpipe, unless llvmpipe is always indirect-rendered, in which case, yes, it would be slower.