Run time or development time? Runtime is mostly negligible except for places with heavy congestion (caches + rendering) where you can turn the heaviest operations on and off as needed -- in our case the call to `System.getCurrentTimeMillis()` is usually too expensive to do unless we really need it.

In terms of development, it's not a lot of work continuously, but it took some while to write up, test and benchmark standard libraries for eg monitorable semaphores. In general though, what it does is raise the entry threshold for new developers a bit as you need to have a feel for when something requires monitoring and when it doesn't.