V-RAY
Description
Long loading times when V-Ray is activated after installing an update or a new version of V-Ray.
Cause and Solution
The slowdown occurs because V-Ray is updating all V-Ray data in the background (Geometry, materials, etc) to the newer version and it depends on the file size and project complexity.
Note that this would happen only during the first opening. The slowdown will not reoccur after saving the file.
More information regarding migration you can find in the links below:
V-Ray for SketchUp - Migrating from previous versions
V-Ray for Rhino - Migrating from previous versions