Even tho performance has been improved a lot since its release Warmerise uses WebGL which is a pretty new system that not many games use. WebGL consumes more resources from your PC, while Standalone and those who still use Unity web player in Palemoon or other specific browsers like Palemoon consume way less resources and PCs with lower specs can handle them better. Rush Team for example uses WebGL as well and the game feels less smooth than in Standalone and the FPS are capped to 60 or something.
So do not worry, I do also have a pretty good PC which can handle high quality games like CS:GO, Fortnite, PUBG, Overwatch at +200 fps, but in Warmerise I do have around 100 fps max and in full servers it drops down to 50-60.
Have a nice day!