[Prototype optimalization] Shadows vs. transparent gradient

Hi, 

I’m working on a protype that tends to be very slow on older phones. Obvious reasons like too big images etc removed.

I know shadows are one of the things that slow prototype and in past indeed this often was a big effectiveness increase in my protytypes, when I have removed them. However, the protypes I am working on right now has them not just for “beauty” but also as a functional part of UX, so removing them completely could affect usability results I guess. 

I wonder, does anybody know if chaning the shadows to frames with transparent gradients or frames with gradients in mulitply mode would be any better for prototype effectiveness? Or is more like this that anything transparent is so much challenge for Figma proto?

Thanks a lot if anybody could help : )