Suggestion: Place a benchmark result in readme or somewhere else

[ljsnogard]

That would make this performance optimization design more convincing. Consider performance under AOT and JIT conditions would be better.

[ufcpp]

see: https://github.com/dotnet/csharplang/blob/main/proposals/utf8-string-literals.md#examples-today

This is an excuse not to provide benchmarks, but it is a widely known fact that getting UTF-8 bytes from string literals is not efficient.