Best one to select is "No", in my experience, unless you rarely visit pages that have Javascript on them. Good rule of thumb is, if you use Google Docs, GMail, or anything Google, Javascript pausing will make it suck.

Now, I do this with a slight annoyance because you can't get more 'plain' that "Pausing JavaScript" - either you know what Javascript is or you don't... but here goes:

JavaScript is a standard language used for making certain things happen on websites. Basically, there's HTML and CSS, which define how a page is laid out and looks, but doesn't change after being loaded unless you refresh the page. JavaScript is a way of telling the browser that loads the page to perform certain functions - usually create a pop-up yes/no/whatever window, or create a text-box on the screen when you press a button/link - stuff like that.

Anyway, JavaScript Pausing basically pauses the running of JavaScript - I presume it's meant to be a CPU/power saving feature - after a certain amount of time. So if you go to a website that has Javascript in it, your browser will continually check if the conditions in the script are true, and run it if it's something that loops/runs-constantly. This is how normal desktop browsers work, typically. Javascript pausing will simply stop/"pause" Javascript running after a certain amount of time. It's presumably supposed to then resume running Javascript when needed.

Sounds like a great idea, right? Well, it would be, except on sites that are javascript-heavy, like GMail, the browser screws it up, so the page basically ends up running abysmally slow, if it works at all.

Personally, I just leave it off. I don't think you'd ever noticeably make anything run better or with less battery drain by having it on. I certainly never noticed it having any advantage other than screwing up running some sites that actually depend on Javascript.