Java Hello World takes 0.132s on my Macbook pro. If I turn on -Xshare:on to use class data sharing, then it drops to 0.119s. Ergo, Java startup time is non-factor. Graal could make this even quicker, for example, a GraalVM AOT helloworld can be reduced to .008s startup, see https://github.com/graalvm/graalvm-demos/tree/master/java-ko... for example.

"time bazel" returns 0.098s

Running a null build took 0.84s, but Bazel does significantly more work, as it's working on a big monorepo, as both a build tool and a package manager.

In short, it is not a problem. But I've had npm take many many seconds for simple operations. "npm list" takes 2.9 seconds.

Python can be slow, depending on the tool. Waf sounds like it is simple and fast, but there are lots of other examples of slow python frameworks out there.

> "time bazel" returns 0.098s

For me it returns 1.6s on first run, .9s on second (bazel 0.29.1).

    $ time (echo 'quit()' | python)

    real    0m0.025s
    user    0m0.000s
    sys     0m0.031s

    $ time (echo 'quit()' | python3)

    real    0m0.036s
    user    0m0.031s
    sys     0m0.016s

(both are after it was already cached)

Huh; I see < 0.15s.

> so I guess 0.09s is Python's start-up time (and some other overhead)

That is probably mostly Waf startup time. Python itself starts way faster than that (on the order of 10-20ms on my machine).

Startup time in any interpreted language is very quickly simply proportional to the amount of code loaded.

   time python -c ''                               # 0.024s
   time python -c 'import argparse'                # 0.036s
   time python -c 'import argparse, json'          # 0.040s
   time python -c 'import argparse, json, httplib' # 0.065s