I have an old Macbook (4,1) that my friends at the Apple store remind me that I should be replacing. But I'd like to squeeze a bit more life out of it.
The biggest issue has been with memory usage. Chrome has been more and more aggressive about using processes to keep one crashy tab from crashing the whole system, but this is done at the expense of memory consumption. One too many tabs and the poor laptop starts to thrash, which is no fun. At some level of thrashing, the chance of an out-and-out crash gets higher, and then I'm suddenly looking at a blank screen.
Enter OneTab (http://www.one-tab.com/), a Chrome extension that corrals your tabs by doing something fairly straightforward. Rather than keeping hidden tabs open, it suspends the tabs you're not using, freeing up system memory. Restoring a tab set isn't that hard and isn't that slow, and the ones you do have open go faster. In my admittedly brief experience with it, I've managed to avoid having the system start to page, and the tabs that would otherwise chew through memory in the background (looking at you, Google Analytics) get stuck aside for later review.
I'm not the only one who found this and liked it - thanks to Ryan Eby (@eby) for the link, after I complained about a Chrome crash.