We're at 100k LOC between the tests and code so far, running in about 500-600ms. We have a few CPU intensive tests (e.g. cryptography) which I recently moved over to the integration test suite.

With no contention for shared resources and no async/IO, it just function calls running on Bun (JavaScriptCore) which measures function calling latency in nanoseconds. I haven't measured this myself, but the internet seems to suggest JavaScriptCore function calls can run in 2 to 5 nanoseconds.

On a computer with 10 cores, fully concurrent, that would imply 10 billion nanoseconds of CPU time in one wall clock second. At 5 nanoseconds per function call, that would imply a theoretical maximum of 2 billion function calls per second.

Real world is not going to be anywhere close to that performance, but where is the time going otherwise?