Finally, it turned out that PUA is not responsible for the waiting times during the first EXE execution, but my Bitdefender Antivieren software.
Obviously Bitdefender changed something at some point, and that is what most AV programmes now do - they send questionable files to their server to check them there!!!
Unfortunately, Bitdefender does not inform you about this, but you sit waiting in front of your PC and do not even have an increased CPU load, of course, because data transfer does not cause any load.
Even when I temporarily deactivated Bitdefender for my tests, nothing changed in this online check. Since Bitdefender was the last remaining culprit, I uninstalled it and suddenly the spook was over.
I then tested Norton Security. It does the same thing, but at least it displays a message that the AV test may take 15-30 seconds. As this happens every time after the EXE or a DLL has been regenerated, I uninstalled Norton again.
I then installed AVAST Premium Security. This also sends everything to their server after every EXE/DLL change and it also displays a message with the waiting time for this, but here you can easily switch off this functionality. I have done this and since then there are no more waiting times for the initial execution of new/changed EXE/DLL files.