I think it really depends on what kind of big of a sig you mean...
If its like a reletively low KB rate, then its fine. If its like flash or something that makes 56Kers load your sig for 3 minutes its probably too huge...and if its too huge as in pixel width and length it will stretch the tables making things hard to read.
Me? I think you should shrink the size or get a new one instead of making 56K people load a humungeously huge sig in KB.
And tbh i dont think that a normal picture would be too huge...is it bmp? bmp images are retardedly huge, open it in Paint and Save As a jpg...it is reletively the same in quality but its much smaller.
