A well-written Python app using the respective platform's native events through say, watchdog[1] performs perfectly fine for huge numbers of files[t]. The language used isn't at all the problem with Dropbox's performance which has been a problem for as long as they've had a desktop app.

If there's one specific bottleneck (ex: hashing files) then that's a prime candidate for Cython[2] or the plain CPython C-API.

Even when you have dropbox restricted to a small folder with _no IO events at all_ it's still constantly working, which is the real problem and entirely an optimization/design problem.

[1]: https://github.com/gorakhargosh/watchdog

[2]: https://cython.org/

[3]: https://docs.python.org/3/c-api/index.html

[t]: ... except when forced to use kqueue or polling