I've recorded a lot of videos without any issue using ReLive, but when today I started recording, my FPS was about 40 while playing Rainbow Six Siege
My PC: AMD FX-6300, Sapphire Radeon R9 270 DUAL-X OC 2GB, 8GB RAM, Windows 7
What I did since the last, good recording:
-Updated Radeon Software to version 19.1.1
-Tried out AMD Link
-Boosted the GPU (memory, GPU clock, Power control)
Before this I always had fix 60 FPS while recording, but now its under 40.