Pinpoint cause of sluggish computer
The laptop is defective or infected.
For checking infection, run deep antivirus scans by several well-known antivirus products.
If no virus is found, the laptop is defective. As it's new, it's not your job to repair it.
My advice in this case is to return the laptop and ask to be reimbursed. If refused, ask for a replacement. If also refused, ask for repairs. If refused again, you're in trouble.