TaskManager shows no excessive CPU activity...
Well, if it's not CPU constrained, then it's possibly an I/O subsystem problem. Can you check in Windows Performance manager what files are getting high levels of I/O. Here's an example, showing the high level of I/O activity that RB can generate through SQLite journalling.
So much depends on how Airnav are using SQLite in their programming, when they commit transactions, etc. Maybe an area for Airnav to look at for performance tuning in the future.