If you just get over it & use Haskell, things will be fine. You'll get huge gains thanks to a lot of Haskell features & libraries, and you might have to write some more fundamental libraries yourself. Haskell makes that pleasant anyways. Worst-case, using Haskell could end up being a wash vs other languages.
Rewrites aren't always indicative of failures of language or the engineers writing it. They're also a useful mechanism for solidifying control for a VPE-type at a nascent but quickly-growing startup. Especially if said VPE-type wants to push out personnel that were there before them.
Now, we shouldn't blame the tool, but the performance was bad, and the induced race conditions were a dagger to the heart for the project.