Ok taking MaMa's fix one tiny step further (unless it's already been covered in the the forum) I've found a tool allowing us to set the priority of osi.exe just one time and thereafter forget about it.
Background:
http://www.subsim.com/radioroom/show...&postcount=233
http://www.subsim.com/radioroom/show...&postcount=188
The theory being (at least as I understand it) that SH5 is a highly demanding process (particularly with the megamods installed) and that the osi.exe which it communicates with does not respond correctly or somehow quickly enough. By running the osi.exe process at a higher priority, it responds to the incoming requests.
Ok so now for the automation tool. I'm not sure that I'm allowed to link to external file resources so I'll just say google SystemExplorer, install that (Win 7->10 compatible), choose custom install, choose the default Task Manager style view and say no to the security check as it's irrelevant to what we're doing.
It'll install itself, and by default runs at startup and minimises to the task tray which is fine. Run Silent Hunter V and as expected the osi.exe process spawns (and latterly dies when SH5 is closed). So when SH is running, open System Explorer from the task tray, type in osi in the top right filter. The osi.exe process should appear within the main pane, so right click on that and set Process Priority to Real Time and check the Permanent option.
That's all needed. Next time you boot up or run SHV, System Explorer will automatically set the osi to real time priority. Hopefully this works and simplifies the process if tonnage bar is wanted or required.