Synchronization of security definitions takes a lot of time, that greatly increases Handler's startup. To decrease startup time, Security Definitions can be cached, and then replayed during the next startup, instead of receiving via UDP. To turn Security Definitions cache on, Start(Boolean) method should be called with parameter cacheSecurityDefinitions = true. In this mode Handler will search for SecurityDefinitions-Channel_{CHANNEL_ID}.cache file. If file is found, Handler will try to replay security definitions from that file. If file is not found, Handler will listen to definitions feed and store received definitions to SecurityDefinitions-Channel_{CHANNEL_ID}.cache file. This file will be replayed during the next start.

Security definitions can be modified, and, as a result, cache should be reset once a week (during weekend). To do this action, a user just needs to find and delete SecurityDefinitions-Channel_{CHANNEL_ID}.cache file. This file is located in directory, specified by SecurityDefinitionsCacheRoot property.