Happening on or off wifi?

Off wifi, web page load speed is entirely dependent on your carriers network speed, how good your connection is, and how congested the network is in your specific area.

The same applies to your wifi connection, but usually wifi will tend to be faster and more reliable.

For example, I use Visible, a low cost Verizon alternative. Every now and then I will have slow or “throttled” mobile network speeds because the visible network may have lower bandwidth priority vs the actual over-priced Verizon network.