Windows can be quite busy at startup, launching/accessing all programs, pulling in Windows updates, etc....and having a conventional hard drive can often make this process seem like watching paint dry...
You should first make sure all your WIndows updates are pulled in/applied....
Then, see what your task manager/performance says both cpu utilization and disk utilization are, with nothing happening while at true Windows idle...
Even a slow Dell laptop will eventually show only 2-3% processor usage after all download activity is done...
Any strange processes in task manager/processes? (A screenshot would help)
We need to distinguish between possible malware infections, and normal Windows download behavior.
It would be helpful to list your systems specs as well, as Dell Win10 laptops with 4 GB of RAM and 5400 RPM drives are quite slow compared to a 7700K desktop with an M.2 NVME drive....
If impatient, it is normally quite safe to run a cautionary pass with both Malwarebytes JRT as well as Malwarebytes Antimalware...; lack of detected junk and/or malware would be a bonus.