Sidescroll stuff at bottom of page?

[Barleduq]

TL;DR: What is it? Why is it? Is there any metric of how much bandwidth/memory it's using?

I have no need, usually, to scroll to the bottom of the page. However, recently some pages have been short enough that I'm suddenly seeing something scrolling on the bottom of the page - some seem to be wow related (stranglethorn vale fishing contest), others I don't recognize. I do tend to keep a browser window open to this site, in a tab along with things like my wow associated gmail account, my norganna's addons account, and wowhead.

Incidentally, I'm seeing a lot of lag on my computer - a lot of memory used. This continues to be the case when even when I kill things like the desktop launcher, other browser windows, my solitaire game (great for long flights)... in fact, killing everything but my wow window, this browser, and my im client (pidgin). Yes, I know about the hooraw over wowhead's ads, and I killed all the wowhead tabs also, and I'm still seeing it.

Now, I have an older computer, running Linux, with some upgraded components so it's actually not the lowest hardware that will run wow, tho it's certainly not the highest. I expect some issues (but at least I'm no longer consistently at 15 fps). But I looked through the news posts and didn't see anything mentioning this, so I figured I'd ask.

Thanks!
-Barleduq