Software or OS is running slow.
These articles explain why your software or OS is running slow.
Lack of resources (RAM, CPU, HD).
Open task manager and look for RAM/V Memory allocation (any applications use the entire RAM?)
Adjust Virtual Memory if necessary.
Check CPU usage levels.
Check your HD space.
Through Task Manager check the System Processes and look for sketchy names using a lot of CPU/RAM
(Virus can have a similar name to common Windows components).
Perform full System Scan for Viruses. If you have a virus that you can’t remove-consider OS reimage/reinstall.
Install all updates for your computer/Let them finish/reboot (updates can take up resources and time).
Note: you can also upgrade to SSD storage for a huge boost in OS performance