@BearGrillsKills
When you just hit the "X" all it does is minimizes the Client to the part of the taskbar where you see your volume, internet connection, etc. You do a full exit from clicking "Origin" in the top-left corner of the Client and selecting "Exit". You would launch the game before doing this. However, you dont need to. Try disabling Origin In-game, as this is an overlay that is known to cause alot of "Stuttering". See steps outlined below to disable Origin In-game and see if this helps with your issue.
To disable Origin In-Game, follow these steps:
1. Open your Origin Client
2. Click "Origin" in the left corner, and click "Application Settings"
3. Click "Origin In Game" on the left side of the window
4. Un-check the box next to "Enable Origin In Game"
5. Boom...Done
Post back and let me know if this helped with your stuttering or not.