Same thing again, it depends entirely on really specific domain logic. How easy it is to add a new feature on a C based web browser versus one built on Haskell

Same thing again, it depends entirely on really specific domain logic. How easy it is to add a new feature on a C based web browser versus one built on Haskell is mostly useless, it just tells you how quickly one person added one feature on one specific thing. Languages aren't inherently comparable, you can get useful benchmarks but they shouldn't be taken as gospel.