After the first compile (and a bit of the second) the biggest speed issue is the linker, and the mingw linker is not fast.
I suspect adding support for msvc tools will help and I’ll look into it when I get some spare time. But personally speaking, things are usable enough for me, esp. when compared to monkey1 with largish projects (like transcc which was a huge PITA to modify).
The emscripten linker *is* slow and there’s nothing that can be done there. Wasm looks to be a lot faster, but that’s a while off yet.