Highly optimized code tends to be inelegant in any language. That said, you can get really good performance from very elegant looking “normal” Haskell too. The big challenge with performance in Haskell is that the differences between optimized and unoptimized code can be pretty subtle if you’re not used to thinking about Haskell performance.

Let me clarify: naive/beautiful/effortless Haskell code tends to be highly performant, although that is not always true. I believe it is much easier to write fast Haskell code than to write fast C/C++ code.