Oh, I wouldn't use something like this for the main code of a page. You should absolutely just compile and bundle the TS once, rather than on every page load.
But there are cases where you want to be able to run arbitrary TypeScript in the browser - in our case it was inline editable code samples - and for that running the TS compiler efficiently in a worker is great, and 730k isn't that bad. You probably also have 500kB - 1MB for a decent code editor too.
That's totally fair. The OP seems to be intended for your main page logic:
> TypeScript is still second-class citizen with regards to browser adoption, there is a proposal to fix that, but until then we have to use tooling, bundlers, build steps that are an impediment for when you want to quickly create a short demo or PoC.
(Of course, just for "a short demo or PoC," but will anyone be motivated to rip it out before that's no longer feasible?)
So I assumed you were talking about something similar. But using this approach to compile user code makes a lot of sense.
But there are cases where you want to be able to run arbitrary TypeScript in the browser - in our case it was inline editable code samples - and for that running the TS compiler efficiently in a worker is great, and 730k isn't that bad. You probably also have 500kB - 1MB for a decent code editor too.