I think we do not have enough information on whether that is actually true. It’s easy to say llvm slow, therefore Zig slow, but that’s not necessarily true.
When I investigated compile-time performance in my project a while ago I’ve come to the conclusion that it’s not just llvm, but it’s also the fact that too much code is generated from comptime duplication everywhere, allocators, data structures, printing, they all emit the literal exact same assembly code hundreds of times (note that allocators and most data structures only care about size + alignment, printing cares about only some of the text).