Depends a lot. My ISP's (both mobile ISP and DSL) have pretty slow DNS providers. My mobile connections were significantly quicker after I switched to using VPN

Depends a lot. My ISP's (both mobile ISP and DSL) have pretty slow DNS providers. My mobile connections were significantly quicker after I switched to using VPN with Cloudflare DNS as resolver (or even the local resolver, though that is normally a bit slower than Cloudflare/Google DNS due to caching)