Neeko's Ult - Self Stun

When Neeko ult's she slams down right essentially stunning herself? Is this reduced by Tenacity? (The stun on herself)

I have had several games where I stun someone and they break free from the stun faster than Neeko is able to interact again. With Garen I kind of get it cause he had maximum Tenacity but it happened with Elise who had no tenecity. She started moving faster than i could throw out a spell after landing the stun.

This isn't all the time but fairly frequent and I'm wondering how to play around it.