Catalina is checking notarization of unsigned executables

  $ echo $'#!/bin/sh\necho Hello' > /tmp/test.sh && chmod a+x /tmp/test.sh
  $ time /tmp/test.sh && time /tmp/test.sh
  Hello
  
  real 0m0.016s
  user 0m0.002s
  sys 0m0.010s
  Hello
  
  real 0m0.006s
  user 0m0.002s
  sys 0m0.004s

> Some people try to explain away the delay, e.g., "I would put the 300 vs 5 ms down to filesystem caching", but such hand waving doesn't stand up to further scrutiny.

...but does not provide any "further scrutiny", so for me, occam's razor applies.