Having Origin enabled in-game has always caused issues on Macs. As well as causing lagging issues it can also cause your game to not load, something which seems to be becoming more frequent amongst players. So the best thing to do is just disable it. Unfortunately you will have to do this after each Origin update as it annoyingly enables itself each time.
- Open Origin then click on Origin > Preferences in the menu bar
- Click on Origin in-game on the right side
- If Origin is enabled in-game the button will show green. Click on it to turn it off so it looks like the picture above.