MageAlert lower my fps when I play my non-mage alt

Hi. As title says I use Mage Alert, which is an addon I really like and find extremely useful, and there's no problems when I'm playin my mage but as soon as I log with a non-mage alt my fps goes really really low. If I completely disable the addon it solves my problem but I wanna know if theres a way to solve this and still using the addon on my mage since I literally cannot live without it haha.
Would appreciate any support on this.
Have a nice day.

In character selection screen when you press addons button, you can first disable the addon, then in a dropdown at the top select your mage and enable the addon only for that character.

Thanks for the response. I though I needed a new addon or something but being able to do it in the game directly is amazing. Cheers