It's a tradeoff. Do you want your code to run as if it was written by hand (i.e. duplicated by hand)? Then monomorphization is best.
For Rust, it makes a lot of sense to pay for some compile speed penalty to not have any performance penalty.
For Rust, it makes a lot of sense to pay for some compile speed penalty to not have any performance penalty.
That's the key phrase in his statement.
I'm not familiar with Rust, but if compilation speed is a major issue, and there are aspects of the compilation that are avoidable to trade-off for runtime performance, it seems to be a good idea to make those configurable per-build-type. Does Rust not offer this?
For many applications debug builds are fast enough, but their runtime performance is already so slow, that I hope they don't get even slower.
That's not always true because monomorphization where the vast majority of the object code is the same in all actual cases means bloating the text of the program, which means putting pressure on the Icache, which means more cache misses, which... is slow.