The things that make a computer slow are:
1.Not enough free space on hard drive
2. Excessive fragmenting on hard drive
3. Virtual memory setting wrong
4. Application resources not released, solve by rebooting
You can check the free space in My Computer, right click on the hard drive and select properties. It will show a graph to indicate how much of the disk drive is used and how much free space. In the tools section of the drive properties are the defrag tool.
Virtual memory is found in the (Windows 10) System-advanced system settings. Checked the Advanced tab and click on settings, click on advanced and you will see the virtual memory setting. Click on virtual memory settings to see if it is set to automatically adjust or if it is set manually, if it is set manually then you can increase the virtual memory. Virtual memory is a place where the OS can store and load data, it uses part of the hard drive as the virtual memory.
Other things to check: Updates, drivers and check for malware.