Wow, I have never seen such bad timings before. Hmm, I would actually recommend to first of all make a backup of your current OBS settings (thats in %appdata%\OBS), move that folder somewhere else (OBS should be closed while you do that) then start OBS.
It will start as if you just installed it. Now just setup the most necessary settings, bitrate/resolution and add a gamecapture for your game. Then please do a test recording of 3-5 minutes and see if you get the high cpu usage warning. After you are finished and if you had problems, you can upload the "current" log file from within OBS and link it to us please.