Posterize time ridiculously laggy

I'm trying to add a posterize time effect to tiny little clips in my premiere timeline, really only about 3 seconds long. There's nothing even really happening in the clips, it's just images zooming in and out so it shouldn't be that there's just too many complicated graphics/too many high res videos/images but as soon as I put one little posterize time effect on one of these small sections, premiere freezes, refuses to do anything and sometimes crashes. My mac was brand new this time last year and also has a lot of storage. There are so many other things I manage to do on Premiere that are so much more complex than this.