I noticed this while looking at the source code.

Runtime.run is marked async:

But then when we call pyodide we do the following:

Note the return await, which should probably be just a return. I'm not fully sure of the implications of doing the await here but I guess it causes code to be less parallel that it should be.

I think that it means that if we do the following:

await Promise.all([
    runtime.run(src1),
    runtime.run(src2),
    runtime.run(src3)
]);

src1, src2 and src3 will not be executed in parallel but sequentially.

In general, I think we have a problem with our usage of async in our codebase: we use them a bit too freely and without really understanding what's going on (or at least: personally I don't fully understand what's going on: if you do, please explain to me :)).