Your Phoronix link shows clang as faster than GCC (more is better on the graph). The benchmark game results seem to go back and forth.

I don't think that it's convincing evidence that clang is slower than GCC.

Yes, you are right. I think they are head-to-head nowadays.

I was thinking about, and meaning to post that one, but got the wrong search result:

https://www.phoronix.com/review/clang20-gcc15-amd-znver5/5

But they swapped places a few times over the last years, so basically there doesn't seem to be a fundamental difference in performance anymore.