Less graphics power all the sudden (Intel HD 3000)
Solution 1:
I know Intel has had a number of issues with the Linux kernel driver, As these articles will show.
Tweaks To Extend The Battery Life Of Intel Linux Notebooks
RC6 power savings Disabled For Linux 3.2
however if you are comfortable with adding kernel command-line parameters you might try using the i915.i915_enable_rc6=1 or the pcie_aspm=force option to get your graphics back up to par. Just be on the lookout for possible overheating and/or lockups.