Tor: Why is Tor Browser slower than my regular browser?

Short answer

Tor traffic crosses multiple relays, and the capacity and latency of those volunteer-operated relays vary. A distant or overloaded website can also be the bottleneck. Try the page again, test another site, and check whether a bridge adds delay. Slowness alone does not mean Tor is malfunctioning; do not weaken browser security settings merely to chase speed.

Sources

Tor Project: Browser speed, Tor Project: Troubleshooting.