A client’s device was recently used by multiple other users.

Comprehensive and Detailed In-Depth Explanation:

The two best first steps are:

Perform a virus scan – Multiple users on a device increase the risk of malware, which can cause performance issues.

Check the startup programs – Unnecessary programs running at startup can slow down the system.

C. Back up the data – Important but not the first step for performance troubleshooting.

D. Disable the guest account – May prevent future unauthorized use but does not immediately fix the current issue.

E. Update the firmware – Firmware updates improve hardware stability but are unlikely to fix a sudden performance drop.

F. Reinstall the operating system – A last resort, as it erases data and takes significant time.