Haskell tips/why doesnt this scale linearly?
Just a quick observation: as the length of values and centers increase, the list indexes (!!) are increasingly inefficient. Try values :: Vector Float, centers :: Vector Center with Data.Vector.(!) and see if performance improves.

I'm trying to see what other improvements can be made, I have a few in mind but its difficult to understand how your code works without the full program. Would you mind linking to a pastebin?