When opening a Visual Overview for the first time, the Visio file (Vsdx or Vdx extension) is downloaded from the server. The Visio file is in reality a container for different files (xml data, images, etc).

Upon receiving the Visio file, the Visual Overview engine processes the xml structure and translates this to the Visual Overview data structure. This new data structure contains multiple optimizations and is enhanced with a DataMiner context. It's this new data structure which is then saved in the Visio cache folder on the client's machine.

So loading from the Visio cache reduces loading times in 2 areas:

1. The file does not need to be fetched from the server, instead it can be read out from the disk which is significantly faster.
2. The processing of the xml structure is no longer required as this was done prior to saving the file to the cache.

Note that there is also a memory cache which contains the last opened Visual Overviews opened by the Cube application.

A failure to deserialize a cached file typically means that the data structure in the cached file no longer matches the structure of the Cube application. There are different safety checks that should prevent this from occurring like versioning and comparing the last modified time of the files.