Updated
Quick fix
Restart the computer (a real restart, not just closing the lid), install updates, then check Task Manager (Windows) or Activity Monitor (Mac) for programs using lots of CPU or memory. Trim startup apps and keep some disk space free.
Step by step
Restart
Many computers are “slept” for weeks. Choose Restart from the Start menu (Windows) or Apple menu (Mac).
Install updates
Windows: Settings > Windows Update. Mac: System Settings > General > Software Update. See updates.
See what’s using the computer
Windows: press Ctrl + Shift + Esc to open Task Manager. Mac: open Activity Monitor from Applications > Utilities. Sort by CPU or Memory to find heavy programs.
Trim startup apps
Windows: in Task Manager, open Startup apps and disable ones you don’t need at startup. Mac: System Settings > General > Login Items.
Free up disk space
Keep at least 10–15% of the drive free. Empty the Recycle Bin or Trash and remove large files you don’t need.
Close extra browser tabs
Dozens of open tabs and extensions use a lot of memory. Remove extensions you don’t use.
Scan for malware
Run your antivirus or a Microsoft Defender scan. Unexpected pop-ups or new toolbars are warning signs.
Consider the hardware
Older computers with spinning hard drives or little memory may need an upgrade (such as a solid-state drive) or replacement.