I'm guessing you mean the core work from PUB rather than the leg work in PLB. Suzanne Deason's Balance Ball ab workout has similar moves that are Pilates paced. By that I mean, slow & controlled with an emphasis on quality over quantity. She doesn't do the full pike, just the one where you bend your knees as you pull the ball toward your chest. Deason is very low key (just in case that's an issue). And make sure you get the ab workout not the total body compilation which has a condensed ab workout without the planks.
I can't do the Intensity Series core work at the same pace as Cathe & crew & maintain good form so I just go out my own pace. So you're not alone.
Debra