Hmm, quick update. The reason I wanted to go back to stable is because I was having choppy, lagging scrolling on certain websites, such as this one:
And also my Netvibes homepage. I didn't have the problem a few weeks ago. I don't know what about those pages was so hard to process, but I assumed it was a graphics driver issue (my RAM usage never goes above 20 %), and that something must have changed in the kernel.
However, when I went to do the downgrade, I realized the kernel hadn't even changed--still 3.10.17. But I decided to change back anyway, and it fixed the issue. No more lagging.
I wonder what the culprit was? Maybe Firefox?