Fps?

[MrDorknessX]

A game working on my PC on 55 Fps
When I am recording it will the Fps will become lower?

[FBX Recorder]

It depends how hard that game is loading the PC. Give it a try. You can reduce the amount of resources FBX uses by going to the Settings -> Video tab and making sure you're using a hardware encoder, reducing the FPS and resolution.