This is beta 5 for version 3.7.1 of POV-Ray.
With this build we've restored most of the performance lost during earlier development of POV-Ray 3.7.1 in user-defined functions (and thus isosurfaces) as well as some patterns with special turbulence handling. Between the migration to VS 2015 and the AVX2/FMA3-specific optimized noise, this now gives us a nice net speed boost on modern Windows systems compared to 3.7.0.