This include:

Is used for wmemchr optimization, it was introcuded in 2024.

The <cwchar> brings in <intrin.h>, which we have always been avoided for throughput reasons. Probably it started bringing it in specifically for wmemchr optimization.

What should we do now? I see three opposite paths forward:

• Drop #include <cwchar> and current wmemchr optimizations. Almost no impact as vector_algorithms.cpp is preferred most of the time anyway.
• Get SDK fixed to use <intrin0.h>.
• Do nothing, accept throughput impact.