The CacheToDisk property of the SectionDocument object tells ActiveReports whether to hold resources in memory, or cache them somewhere on your disk. Caching resources slows processing time, but can save you from running out of memory with very large reports.
If you use the CacheToDisk property without setting a CacheToDiskLocation, the default location in which it caches resources is IsolatedStorage, so you must have IsolatedStorageFilePermission in order to use it. The cache capacity for IsolatedStorage may depend on your configuration, but does not exceed 3 GB.
To avoid using IsolatedStorage, you can specify a folder in the CacheToDiskLocation property. The cache capacity for a disk location is 3 GB.
For an example of the code used to turn on CacheToDisk and specify a folder, see the CacheToDiskLocation property in the Class Library documentation.