Engine performance on older mobile devices based on total number of material tags

I’d have to double check the code to remind myself a little bit.
I don’t remember the details good enough.

I was wondering if having less predicates can helps with performance

It sounds like you’re having performance problems so I suggest you look into profiling.
In general, different predicates will trigger a different draw calls, however even a low end device should be able to handle 32 draw calls imho, so perhaps it’s something different that takes time for you?
E:g. a script?