Keycaps? Does it affect my performance?

Yes! Especially if you're sensitive with it! Mostly stock keycaps of mechanical keyboards nowadays are made of ABS.
ABS plastic is light, easy to produce, also easy to customize, that's why they goes mainstream in keycap markets. For less resonance and heavier keycap that makes lighter on typing, use PBT plastic material keycaps which is harder to produce despite it's hard material. PBT keycaps are also thicker than ABS. The lightest to type (so it's the heavier material) is metal keycaps, but they're really expensive that a set of 37 metal keycaps can afford a new mechanical keyboard!

(those 37 blue keycaps are from PBT material, the others black rubber coated are ABS)

(metal keycaps)
Now the vice versa, the lighter to type means the slower the keyboard key rebounds (the force/speed of the keyboard key/switch from pressed to unpressed). Especially for some games which need fast rebound. But more force means harder to press too, makes the fingers tired too fast (especially typing). If it's about typing, the feel is more important than minimizing the latency of rebound. Of course because there's no way a person would type on a same key.