Thanks a lot for your replay.
I just wanted to post how I solved that problem.
For a test the focuser was not installed directly via the ASCOM driver, but using the POTH system of the ASCOM drivers, in which you can define devices in a “relescope hub” which allows that several programs can simultaneously use the devices. Thanks Hansjörg for the Tip.
This way, SGP now connects fast and there are no lags.
Thanks & best regards