If FileMaker Pro is not in front, after about 10 sec., the FileMaker Access on the other Mac-client is very, very slow.
macOS slows down inactive processes. more then in older macOS versions.
A possible solution: run terminal command after each start of the FileMaker:
sudo renice -n -20 $(pgrep FileMaker)
but then you have to enter admin password.
Is there another solution for FileMaker Pro without manual steps?