Yes it is, so just copying images and posting them in unedited 'willy-nilly' will soon eat that all up.
I use the ms windows snipping tool, paste it into paint.net, save as jpeg to a folder and insert from file. That way my images drop from multi megabytes down to a few hundred K at most.
If there's a more efficient way to do it (and I'm sure there is, I think there are other screen grab utilities that will shrink the final image and reformat), I'm all ears!