Sig size

Unless you're trying to use an animated avatar, there's no reason to need more than 120k. An uncompressed 150x150 32 bit image requires well under that figure. If you're using GIFs and you crop the image to the circular frame, you could easily have 7 frames in 120k. My 26 frame 500x125 animated signature weighs in at (well) under 120k.

As an example, here is KA's avatar with 8 frames using 91k (and not marred by whatever strange compression he used)