1) Don't use multiple Game Captures. They can conflict with each other.
2) Avoid using Display Captures. They are the least-performant capture method. If you MUST use one, keep it in its own scene with no Window or Game Captures, as they can interfere and cause performance issues. Likewise, only use ONE display capture per monitor. Multiple pointing at the same monitor will cause performance issues.
3) As you're already running OBS as Admin, you'll need to limit your game's framerate either via an in-game frame limiter, or enabling vsync. You can also turn down visual options to try to free up some GPU time. The OBS fps drop is because it's unable to complete its housekeeping tasks in time, most commonly because the game is hogging all the GPU.