I've got the same problem:
Very start you will see it's like 150 FPS from before OBS opens in the background.
Quickly it drops to about 40 FPS while I have Multi-Adaptor Compatibility on.
I tab out once to check that OBS is viewing it.
The Second time is where I tab out and disable Multi-Adaptor Compatibility off (which is what I've previously been on) and running smoothly.
This time the FPS is at around 10 fps! (Not in the recording from Ge-force Overlay randomly flickers!)
osu settings: FPS capped 240 - Fullscreen 768p (on a 1080p) with Letterboxing!
Video:
https://puu.sh/yEikz/aee0691f54.mp4 (Video is 50mbs~ so will take a while to load
WARNING THE VIDEO STARTS TO FLASH NEAR THE ENDI first noticed this while I was on Twitch and had swapped from Rocket League to osu!
https://www.twitch.tv/videos/208404587?t=00h57m19sThe only thing I can really think has to do with this is the recent Windows Update that had happened on my Computer! As of writing this I'm updating Graphical Drivers to see if that will help fix the problem!