Thank you for the message. Unfortunately, setting the priority to 'Real time' is not recommended by Microsoft, because when this is done, a process can actually get worse, taking up so much CPU time that Windows itself actually starts to struggle, and this causes processes, even the ones with Real-time priority, to actually perform worse.
Another problem is that services usually do not have configuration, because reasing from a configuration file is not really straightforward for a service (it runs as a sevice, meaning usually the configuration file would need to be in the System directory, and I do not want to place user files in the system folder). There are other options, like reading settings from the registry, but this makes the application more prone to not working, due to things like permissions.
So all and all, it is a complicated issue to want to add a setting to a serviice, and moreover it is likely to not work as well as one might expect to increase the priority further.
It is also very likely that what you are actually experiencing is not something that can be remedies by an increase of priority. You mention large cities - this suggests that, despite your powerful hardware, the bottleneck may be your hardware, either polygon count or data access from disk.
Sorry that I cannot do something to completely get rid of stutters, like increasing the priority of the process further.