Snooping is now more than a solitary, strange online activity today. It is organzied. Companies, governments, organizations, cabals, gangs...there are so many people and groups of people deliberately intruding in your network to see what data is being sent / received - personal details, transactions, etc.
VPNs (Virtual Private Networks) provide a layer of security to your internet access, putting a restriction on who are on your line, so to speak.
Basically, a VPN adds security to unprotected Wi-Fi networks. It protects your browsing habits from ISP, who track all internet activity, all activity. Period.
A VPN provides privacy by hiding your real location from websites.
A good VPN service minimizes 'lag' because your computer / device's actual address is being hidden first. A good VPS doesn't slow your net connection that you will have to notice, most of the time.
You can find a VPN provider with consistent quality on specialist websites such as Best10VPN.