It's well-known that musl is in general much, much slower than glibc. People keep rediscovering that for some reason, likely because they hear of stuff like old echoes of Usenet posts ranting against glob "bloat", not being aware that a lot of what people call bloat is specialization of a lot of performance-sensitive algorithms to leverage SIMD, special-casing, math optimisations, etc.
When you check the glibc mailing lists, it's obvious performance is a predominant concern.