Howard Oakley solves all your Mac hardware, software and iOS issues
QI bought a new iMac (Retina 4K, 21.5-inch, Late 2015), which worked fine until I updated to macOS 10.13.3. Now it runs very slowly, with Microsoft Office apps taking two minutes to open, and Pages up to a minute. I also have Kaspersky and Avira antivirus products installed. Can you help to restore my Mac’s former speed?
AEtreCheck (free, etrecheck.com) is a valuable tool for resolving performance problems like yours, and antivirus software is the most likely cause here. Run EtreCheck and attend to anything it recommends, then uninstall both those antivirus products and run it again.
Some antivirus tools can be persistent and tricky to remove. Their most important components will be installed in the LaunchAgents and LaunchDaemons folders in /Library and ~/Library – the tilde (~) meaning the path to your user account’s Home folder. Filenames in those locations usually make it clear enough which files belong to which apps. Before you remove any, make a full backup of your Mac; if in doubt, check the support site for your software, as some developers list files made by their apps.
Once you’ve cleared out traces of your current antivirus products, restarted your Mac and restored performance, try replacements: Malwarebytes (free, malwarebytes.com/mac), DetectX (donationware, sqwarq.com) and tools from Objective-See (objective-see.com). These shouldn’t impose the same load on your Mac, but are well maintained and arguably provide even better protection from malware.
It’s also important to keep all security software up to date, to ensure it remains fully effective against malware, and to maintain its compatibility with newer versions of macOS.