I have NO idea why your file sizes should be so large when making an avatar! Do you save it as a .jpg? Because if you're only saving it as a .psd, then you need to also save it as a .jpg and the file size should be much smaller, and it will ask you what quality you want to save it as and you can lower the quality to make the image smaller
As for lowering an animated banner/avatar's kbs, that's pretty hard to do without making it look bad

Sorry!
I hope this helps!
