No it is not good. You should normally have at least about 60fps, but it is no big problem if not. 100fps is … more than enough.
I suppose you’re right, 100 fps is more than enough to run a game on. I’m just concerned about adding more entities to the screen and that slowing down the game even further
50 is fine. 60 is perfect. Any more is a waste. Any less and it’ll look cheap.
Cas 
You also should take into account what type of machine you’re running performance tests on before you question your results.
I realize it doesn’t matter much for a personal project, but if you ever ship a game, when people start calling in saying they can’t get more than 20 fps, you can’t say “Well I got 100 on my dev machine…” So test on a machine representative of what your audience is, and you won’t be mislead.