EDIT II: Actually, the problem seems to be "Prismatik". Which is an ambilight program that reads the monitor's side's colors and sends that information to LEDs behind your monitor. Destiny simply "gives up" on frame-pacing as soon as anything that isn't static affects the second monitor. That being live wallpapers (Wallpaper Engine), moving GUI/icons (Rainmeter) or livestreams/videos (YouTube, Twitch, etc)... Rainmeter is a really well-known program used by tons of people, and many might think the game is the problem when they're getting good framerates (I'm getting an average of 110fps) but the game feels like it's running at an inconsistent, ~40fps framerate. The frame-pacing goes to sh*t as soon as something that moves (video, livestream, live wallpaper, GUI) affects the second monitor. It's as if the game thinks it isn't being the focus so it doesn't need to worry about frame-pacing. But if you stop the video, livestream, live wallpaper, etc. the frame-pacing goes back to being perfect. EDIT I: I just minimized Google Chrome that had a YouTube video playing in the background and the game started running well again. It really seems to just be the fact that something is moving on the second monitor.