Slow sandbox start due to Deno type-checking

[teleclimber]

I've been noticing slow to very slow sandbox start times (multiple seconds).

I think Deno is doing type checking of certain files on every run, possible the bootstrap.js file because we re-write it on each run.

I think I do want type checking for app installation, but maybe not while running in normal use.

I could also possibly solve this by not re-writing the bootstrap js file of course.