Comment 67 for bug 665546

Sorry for the string of comments but I've got one more piece of information. As Roger posted above setting visual effects to none appears to solve the problem. However that is not the end of it. Using the Edit menus approach in my previous post I visited some but not all of the menus while visual effects were disabled. They all popped up immediately. Then I changed visual effects back to 'extra' and immediately went through the Applications menu. All of the menus I 'touched' while effects were off came up on the first visit while none of the ones I did not 'touch' did.

So this tells me that the root cause of the odd behavior exists irregardless of which visual effect mode is being used. It is just that without effects it does not manifest itself. I feel this reinforces my theory that we are violating timing somewhere due to a stack up of delays with cache hits/misses likely causing the timing variation. Using visual effects uses up enough of the timing margin to push cache misses into causing problems.

Sadly I'm not familiar with how the mouse movement drives menu display through all of the library layers so I have no idea where to look in source code to continue further. I'll have to leave that to the devs and hope that these observations prove fruitful.