Photos appear pixellated after edit

[One Sock]

This is annoying. A lot of times when I apply an editing step on my photos--changing white balance, exposure, sharpening, or whatever--the picture appears slightly pixellated. Then when I move the mouse over the picture (or sometimes I have to drag the picture around a bit) the pixellated effect disappears. Here's what I mean:

This (above) is a printscreen capture, before any editing.

This is immediately after applying sharpening. The pixellated look is especially noticeable on the whiskers.

I drag the picture slightly, and the pixellated look disappears.