For C++ in my experience clang is much faster, especially for plain (unoptimized) builds.

That has reversed in the last few releases of clang for my codebase.

Because gcc got faster or because clang got slower?

Because clang got a LOT slower and GCC got a bit faster. clang used to be incredibly fast and used little memory consumption, but recent versions have seen the compiler regress in both areas. On the other hand clang does a lot more now than it used to so it's somewhat justified.

My own experience with a substantial codebase (1+ million lines of code) is MSVC uses the least amount of RAM, followed by clang and then GCC. For performance in terms of compiling/linking it's GCC/clang tied and then MSVC from fastest to slowest.

MSVC would be really great if MSFT could solve their small file io overhead and enabled a mode where I could disable file modification notifications completely. Right now doing any compilation makes the anti viruses go completely crazy.

Add the workspace folder as an exclusion to your AV.

On corporate machines you dont know how many things are subscribing to file notifications.