This extreme foot pain causes you to need to stop and loosen your boots.
The common reason for this is boots (including bindings for snowboarding) have been done up too tight!
The biggest reason for doing boots and bindings up too tight is heel lift. If you feel like you don’t get enough grip in the heel area of the boots you will naturally tighten your boots up alot to compensate. Over a certain point (different for everyone and every type of boot) you will only serve to crush your foot, cutting off blood supply and causing massive pain. If you have had this, you will know about it!
If you think your boots are too big then a Volume Reducer may also be required to snug up the whole foot in your boots.