Have you tried OBS studio?
lots of people use that for recording...
OBS (Open Broadcaster Software) is free and open source software for video recording and live streaming. Stream to Twitch, YouTube and many other providers or record your own videos with high quality H264 / AAC encoding.
as for detailed tutorials there are plenty on youtube.
what are your PC's specs anyway, and what do you think's causing your FPS to drop like that.