There is a fairly significant performance regression in 5.6 (in respect to 5.5 & 5.4) when measured using the Mobile Torture test project:

In 'Sprite Animation test' the count of objects rendered at 60fps dropped from ~1000/900 (iPad Pro, Google Pixel respectively) to 820/279. The drop in 'Sprite Rendering test' is also quite noticeable (see google doc linked in comment).

This is is reproducible on iOS (tested iPad pro and iPhone 7) and Android (Google Pixel and Nvidia Shield TV)

Tested on 5.3.4p4, 5.5.0p2 & 5.6.0b3.