> But when it comes to brute forcing then being faster works against you,

We are probably still talking less than an order of magnitude. So that slowness isn't going to save the day in theory. It might in practice but if it comes that close, the implementation will be deemed broken and something else will be advocated.

However a slow function means a lot of cumulative power and time wasted in the years to come to execute this new hash function. So I'd opt for a faster one.