Midi Controller note lag with a few tracks playing

[Thomas Anthony]

I have struggling for a while now trying to get my midi controller to work with protools 11. I am using a simple m-audio key station 61 midi controller (USB to my iMac). I just recently started using protools and I am currently working on a song that only has a few tracks. In those 3 tracks i have one insert each. Grand piano, Boom and another grand piano. Trying to use a 4th track with Structure for synth sound and while the other tracks are playing I'm trying to use the 4th track with structure synth to play along with the rest of the song and Im getting a serious note lag/note hanging while I'm trying to play. Please help!

The frustration is too much. I've been looking everywhere for solution. Youtube, Google, Groove3 teaching videos, etc. Please help

Thank you for your thoughts and input. Stay safe and god bless.

TA