GIF sizes?

I've been once told tht the size of your GIFs made with movie mode can change... but how? I can't seem to find info on it. Is it even possible? I know 640x400 GIFs cost too much memory, but perhaps you could make videos with them if you record audio with Audacity or something...

gif_downscale off

Turn on gif_optimize while you're at it.

Options -> Data Options -> Screenshot Options can do that as well if you don't like getting your hands dirty in the console.

That all sounds well and good, but what does optimizing do for the quality of the image? I mean, there's gotta be a reason why optimizing the image for lower filesizes isn't on by default right?

It defaults on in later versions, it defaulted to off in 2.1.0 because I thought the Chrome issue was related to it (it wasn't).

Optimizing makes the game only output the smallest region that contains all the changed pixels, to reduce filesize. It doesn't help much in active gameplay when the entire screen is shifting, but it does help a lot more for more static screens or gameplay shots where the camera is still.