Whenever I watch videos, either online of local via Totem and/or open PDF files using evince.
The system gets really, really bogged down. All apps get really slow, menus take forever to display, switching windows gives me time to make a coffee, etc.
I've purged Adobe Flash from the system, but YouTube HTML5 videos still have the issue. A bunch of PDFs saved locally trigger the problem.
And to (temporarily) remove the slowness, I need to shutdown the computer, breath for a few minutes, then restart. A simple reboot does not do the trick.
How can I identify the cause?
This only started on 13.04. I've had Ubuntu on this machine for a year without a problem until "upgrading" to 13.04. I am not a programmer, but I suspect an issue with the Intel video driver.
Is there something I can run which will diagnose this, or are there concrete steps I can follow to find the culprit?
I have run some hw tests (memtest86+, cpuburn, smarttools), they do not give any errors.