Originally Posted by HanneSThEGreaT
OK, if the the pictureboxes contain only small graphics, it shouldn't be something to worry about (IMHO).
What I'd suggest you do is to test this particular issue.
Run the program, and let the Timer clear those boxes (the whole time ) - so basically keep the program running for (let's say) a minute, even 2 minutes. If you haven't seen a loss in performance, you should be fine. If you see that the clearing of the pictures become a bit slower, or even the program "works" slower, you'll have a problem
At least, that's what I would do :)