We haven't changed anything major, the only reason for downloading "thousands of new files" is either:
- It was a long time since the last time you installed GSX.
OR
- You installed another simulator in between two GSX updates. For example, if you had FSX and run the FSDT Live Updates regularly, if you installed P3D4/5 and you DON'T also install the full GSX P3D installer, it will download ALL P3D models and textures, and vice-versa if you had P3D and then installed FSX without running the full FSX installer.