This new release finally solves the problem with long recompile times when running in meteor test/watch or meteor run incremental rebuild mode plus it also makes one-shot builds faster by only compiling the typescript sources once across all architectures.
For our code base with about 500 transpiled files for the client, this means that web.browser rebuilds and reloads in about 10 seconds on a 4-year old MBP and server side changes recompile and restart in about 30 seconds (of which 5 seconds are spent on Typescript).
Try it out!
Details:
This was made possible by moving the compilation to use typescript watch+incremental mode.
Caveat: This also means that Typescript and the meteor build system both watch the same source files for changes and race conditions may happen (meteor may recompile before Typescript notices that a file has changed).