A technician is fixing a very slow computer. Antivirus and Malware programs have been run, and some detections have been removed. After running Disk Cleanup, the system still seems to be slow…

CHKDSK checks for and repairs file system errors and bad sectors, but it does not address performance degradation caused by fragmentation.

Manually erasing cookies only affects browser-stored session data and has no impact on overall system or multi-application performance.

Reverting to a restore point would undo recent changes but could also remove legitimate software and does not target a performance-related root cause.

Disk defragmentation reorganizes fragmented files on the hard drive so the read/write head can access data more efficiently. When multiple programs run slowly, fragmentation causes the disk to perform excessive seeks. Running defrag after disk cleanup consolidates free space and file clusters, directly improving multi-program performance.