Compiler Flag Benchmarks

[mukut1994]

Let's say you have big csproj where a build takes minutes to complete.
At some point it might become long enough that the dev has to look for ways to reduce the build time.

Features such as implicit usings don't affect runtime, but compile time.
There could be a scenario where implicit usings is using a large amount of the compilers' time while only adding a few references to System.
In such a case it could be would be better to set disable and have a manually written file.

Benchmarks between language versions would also be interesting, and there are probably other flags which add an overhead during compile time.