Mouse, Stuttering and lagging issues as of the new update

Upon loading into my Minecraft Realm, I am experiencing stuttering and lag, especially when moving around or looking around. In addition, when I move my mouse to the right side of my screen, the cursor travels onto my second monitor. This causes the game to lose focus, which stops my movement and temporarily prevents me from looking around until I click back into the game window.

I am certain this issue is caused by the most recent hotfix, because prior to the update the game was working perfectly with no issues. While I do use addons, none of these problems existed before the update. I also tested this in a world with no addons, and the exact same problems still occurred.