There's nothing in your screenshots that indicate significant system resource usage, or any problem. I do recommend you uninstall Sophos, as it can actually increase a Mac's vulnerability, as described here and here. 3rd party antivirus apps are not needed to keep a Mac malware-free, as long as the user practices safe computing, as described in the following link.
If anyone insists on running antivirus for some reason, ClamXav (which is free) is one of the best choices, since it isn't a resource hog, detects both Mac and Windows malware and doesn't run with elevated privileges.
System Performance "The computer is running unusually slowly although it is not experiencing abnormally high CPU utilization.
Application icons may "bounce" in the Dock for an extended amount of time when launched.
Applications may not function correctly or may stop responding after being opened."