CheckMK version 2.0.0P1 vs CheckMK version 2.0.0p16 (CRE): Agent takes nearly double time to answer

On this machine you should take a look at the agent log file.
For this you should see at what point it needs the time.
A single call of the agent will start with a line like this.

2021-10-13 13:47:16.144 [srv 25960] Connected from '172....

The last line of such a communication would be something like this

2021-10-13 13:47:16.886 [srv 25960] perf: Answer is ready in [733] milliseconds
2021-10-13 13:47:16.886 [srv 25960] Send [71538] bytes of data
2021-10-13 13:47:16.948 [srv 25960] perf:  In [431] milliseconds process 'powershell.....

After the “send” it outputs the line for async plugin processing.
You see in my case here the complete agent processing took around 700 millieseconds.