The plugin manager support caching data at two level.
The content of the repositories. This enables to load the content of the repositories without requiring fetching them again.
The plugin themselves. Once downloaded, or deleted, plugins can be added to the cache. The cached plugins are version dependent.
The cache can be enabled/disabled in groimp options.
The cached data can be deleted by the plugin manager.
The default cache directories are: /home/.grogra.de-platform/pluginmngr_cache_plugin/ and /home/.grogra.de-platform/pluginmngr_cache_repo/