Some programs on installation insert themselves into the Startup menu which can unnecessarily use up memory and have an impact on performance.
On my Win 7 laptop I don't have anything checked in my Startup menu and non-MS services are heavily vetted so the machine will run as lean as possible.
Some of those services I uncheck include program updaters, but you may want to leave those enabled.
To check yours, go Start - type msconfig and press enter then click on the Startup tab to see what is checked.
Which antivirus program are you using as some have been known to slow a machine down.
As you have reinstalled, there may be quite a few temp files which could do with a clean out.
You could go Start - type disk cleanup and right click on it when it comes up to select Run as administrator - that will clean out some, including any superseded Windows Updates.
This article is a guide as to what you can safely clean out. -
https://www.howtogeek.com/266337/what-should-i-remove-in-disk-cleanup-on-windows/I recently factory reset an OEM laptop and ran Disk Cleanup in that mode and was surprised that it found some to clean out as the updates had just been installed.
However, I use the free version of CCleaner to clean out temp files -
https://www.piriform.com/ccleaner/downloadTo ensure it cleans out as much as possible, click on Options/Advanced and uncheck the box for only clean out files older than 24hrs.
Also under Options, click on Monitoring and uncheck those boxes.
As you have done a clean install then it's unlikely that it's the OS that is causing problems but what you have installed since.
To find out if it's any of those that are causing those alerts, in msconfig, under the Startup tab, click on Disable all - Apply - OK - Restart.
If you still get those alerts for Dashlane and/or SnagIt, go back into msconfig and under the Services tab check the box to Hide all Microsoft services.
Note which are showing as Stopped then click on Disable all - Apply - OK - Restart.
An AV program though can reinstate itself.
If the alerts no longer appear after disabling all under the Startup tab, then you can leave those unchecked but if you want to find out what is conflicting, then re-enable one at a time and see what happens after each reboot.
The same would apply if the alerts stopped after disabling all of the non-MS services, but because there's usually more than a few of those, it's advocated that you re-enable a few at a time and then check after each reboot.