There isn't really a clear answer to your question. Things like this are very complicated and the only real way to know whether or not it is impacting your fps in a meaningful way would be to download some kind of program that lets your monitor your fps.
Short answer: it depends entirely on how the game itself is coded. The human eye can theoretically only see about 60fps anyway, so your example probably wouldn't have any visible impact even if it is
dropping a little.
If you'd like some well-written reading material on the subject, I suggest the following link: Alt-tCRASH