See the documentation for more details:
Configuring Class CachingWebLogic Server now allows you to enable class caching for faster start ups. Once you enable caching, the server records all the classes loaded until a specific criterion is reached and persists the class definitions in an invisible file. When the server restarts, the cache is checked for validity with the existing code sources and the server uses the cache file to bulk load the same sequence of classes recorded in the previous run. If any change is made to the system classpath or its contents, the cache will be invalidated and re-built on server restart.
The advantages of using class caching are:
The cache uses optimization techniques to minimize the initial cache recording time. Cache recording continues until a specific class has been recorded.
- Reduces server startup time.
- The package level index reduces search time for all classes and resources.