I have an image that I want to convert to png / jpg.
The file size differences for each type is very small (photoshop save-for-web-and-devices optimized):
155 bytes for image.png
357 bytes for image.jpg

I don't care too much about the file type either, because there is no opacity.

Is there any difference in loading speeds for browsers between images types?
say, for example, firefox prefers .png files because they're uncompressed so it loads faster (just a thought).

thanks