How does Symantec Endpoint Protection Cloud affect the performance of user’s machine during definition updates and virus scans?

Definition updates are not monolithic but incremental, and the default scan policy is also tuned for minimal performance impact. Executing an on-demand full system scan will have a minor impact on overall system performance but by default these will only occur if initiated by the end user or admin. The performance of the user’s machine won’t be affected as the services delivered by Symantec Endpoint Protection Cloud has been enhanced by scan performance mitigation and reduced memory usage.