There is a performance regression on A7 devices possibly because of the transition from half4 to float4 for shadowmap coordinates.

To Reproduce:
1. Build (with 5.1 and 5.4) and run the attached project for iOS with Metal on an A7 iPad.
2. Do a frame capture of the rendered scene, observe that:
on 5.4 the standard shader is a ~2ms slower (see attached screenshots).

Reproduced on :

Version 5.4.0f2 (14e9279a8947)
Wed, 20 Jul 2016 15:47:58 GMT
Branch: 5.4/release

Not Reproducible :

Version 5.1.5f1 (9de525f1a6a8)
Wed, 13 Jan 2016 09:23:21 GMT
Branch: 5.1/release

on iPad Air 1

the difference is much less significant on newer devices like Air 2 and above.