When the model holds still, most of Live Skin goes to sleep (the tissue settles and stops being simulated). Once it moves, every painted area wakes up and works every frame, so the cost follows how much you have painted and switched on.
I included PERFORMANCE chips on all settings that can affect FPS as of v3, so you can see at a glance which ones cost frames and tune them to your scene and your computer's capabilities. Turning on Technical Info on the Overview page also shows what each feature costs the CPU live.
I'm also working toward a performance focused update for v4, so you can expect a lot less FPS drop when the model is moving, once it's ready!
Hope for more ways to optimize performance in the future. Tried the paint but was difficult to really get it right and get any meaningful performance gain.
Unfortunately some of those cool features come with a fair bit of extra work for the PC
I'm actively working on performance improvements though, and I'll definitely push updates whenever I find good optimization opportunities. There's a ton to go through, but with time it should only get better.
And I'm with you on the painting, as I've found it a little painful too, especially when trying to work with full or null values meant for performance. That's something I'm planning to improve ASAP as well.
For now, make sure you only toggle on features you're actively using on busy scenes, and watch out for Soft Tissue, Contact Dents, Pressure/Fold Marks and Vellus as they are the most costly currently.
Really appreciate the feedback, and glad you're enjoying it ♡