SPSiteCollectionPropertyCache class
SharePoint 2013
A thread-safe cache that may be used to store very small amounts of data associated with this [Microsoft.SharePoint.SPSite]. Fetch an instance from [Microsoft.SharePoint.SPSite.Cache].
Namespace:
Microsoft.SharePoint.Administration
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
The cache is stored in memory and will be emptied during the next process recycle. Cache entries can be removed during site deletion but object invalidation is not assured. A process recycle may be required to invalidate cached entries. It is critical that only very small values are placed in the cache because the cache has no flush mechanism.