One problem with Wasm is that in practice there's not as much optimization work to do as you might expect, as the higher-level compiler which produced it alread

One problem with Wasm is that in practice there's not as much optimization work to do as you might expect, as the higher-level compiler which produced it already di a lot of the work. Of course you still need to lower the stack machine + locals to actual spills/fills/etc., but still a chunk of the work is already done for you.