The 240Hz monitor upgrade is likely your culprit - those games might be trying to push way more frames than your GPU can handle, causing stuttering as the frame rate fluctuates wildly. Start by capping your frame rate in-game to something your system can maintain consistently, like 60fps or 120fps depending on your hardware, which should eliminate the random dips. If that doesn't help, update your GPU drivers since that's the next most common cause, then check if background processes or driver conflicts are eating resources. One more thing to test: disable any frame-syncing options (like V-sync or G-sync) temporarily to see if those are causing the stutters rather than preventing them.