Seems you're not the only one. Many users have complained about observing a CMD command prompt windows briefly snapping open and then closing immediately on every Windows 10 OS boot. I agree this may be a bit annoying and not the best user experience. It
seems though, that normally you should not even see the popup on screen. I assume there could be many reasons such a laptop lagging behind on startup, though I won't go too deep on that...
First, USO stands for Update Session Orchestrator
and it's the mechanism which replaced the Windows Update Agent. As a part of the
Windows Update service, usoclient.exe main role is basically a command to run tasks to either scan for updates,
install or resume updates.
You can no longer use the old (wuauclt.exe /detectnow) commands to schedule a
Windows Update scan via the command.
Windows Update settings has been moved away from the legacy Windows Control Panel to the new modern
System Settings app in Windows 10.
Therefore, you won't find any reference to usoclient.exe file listed under Control Panel > Uninstall or Change Program list.
The usoclient.exe program is located in the C:/Windows/System32/ folder. Some may have claimed it was okay to delete the
usoclient.exe file manually. I personally wouldn't recommend it but rather simply let it do its job. Deleting the
usoclient.exe file may cause unwanted behaviours...
If you open Task Scheduler and scroll down the scheduled tasks at
Microsoft > Windows > UpdateOrchestrator, you will find options of the
usoclient.exe [Command process and arguments].
If you take Schedule Scan task[to perform a scheduled
Windows Update scan...], the Triggers for this task to run could be
-One Time [At system startup]
-Custom Trigger
-On an event.
If you click on Action Panel, you'll find the usoclient.exe
associated Action: Command and
Argument Details
%systemroot%\System32\usoclient.exe StartScan
Last but not least, the task Status options:
-Ready
-Run
-End
-Disable
-Export
-Delete
So you could simply try disabling it and see what happens...