|Hold down the Ctrl and Alt keys, press Del, let go of all three keys, choose to run Task Manager.|
In the Task Manager - Processes list, click on CPU twice at the top of the CPU column to list the programs so that the ones using the most CPU % activity are at the top of the list.
If the total CPU % shown at the bottom of the window is not high, then the hard drive activity is not significant even when it is active most of the time. .
There are lots of things that tend to run after you have started up the computer the first time on a particular day - the total CPU % will diminish eventually.
When you restart your computer after that on the same day, most of those things will not run right after Windows is loaded initially.
If you see TrustedInstaller.exe, that's associated with Windows Update It can use a lot of CPU % but that will eventually diminish and then it will have no activity at all.
How much free space is left on C ? If that's less than about 10% of the total size of C, your hard drive will be accessed more often. The less free space below about 10% you have on C, the more hard drive activity there will be, the slower everything in Windows will run.