Sembrerebbe così... il caching non l'ho ancora usato, ma
questa cosa me la segno... 
Although the documentations says that CacheManager is safe to use in a
single AppDomain - this is not quite true.
The problem is that the CacheManager is instanced by the CacheFactory.
And the problem is that we need to INSTANCE the CacheFactory (WHY???).
Meaning if you don't keep a single instance of your CacheFactory. You
will end up having two or more CacheMangers in memory, thus each
CacheManager has its own Hashtable. Thus CHAOS.