Document how expensive Compilation.GetSymbolsWithName() is

[aradalvand]

Some analyzers in the wild seem to use tricks like Compilation.GetSymbolsWithName(_ => true).Where(...) to lookup symbols that meet specific conditions relevant to their analyzer logic; the performance characteristics of this approach are unclear, it feels like it would force a full compilation upon each invocation, which if true, would mean it is suboptimal perf-wise, and should therefore be documented so as to discourage its use by performance-mindful analyzer authors.

[Youssef1313]

I think this could be itself an analyzer part of Microsoft.CodeAnalysis.Analyzers package. There is already an analyzer for calling GetSemanticModel IIRC.