Yes. I also written a compiler and I also complained about LLVM.

LLVM is

  - Slow to compile
  - Breaks compilers/doesn't have a stable ABI
  - Optimizes poorly (at least, worse than GCC)

Swift I never used but I tried compiling it once and it was the bottom 2 slowest compiler I ever tested. The only thing nearly as bad was kotlin but 1) I don't actually remember which of these are worse 2) Kotlin wasn't meant to be a CLI compiler, it was meant to compile in the background as a language server so it was designed around that

Mojo... I have things I could say... But I'll stick to this. I talked to engineers there and I asked one how they expected any python developers to use the planned borrow checker. The engineer said "Don't worry about it" ie they didn't have a plan. The nicest thing I can say is they didn't bullshit me 100% of the time when I directly asked a question privately. That's the only nice or neutral thing I could say