Cut signup to the minimum viable fields

Done when

Report the number of fields on the signup form after the cut, out of the number it had before. The after number is lower. (Proof: a count.)

If this is a change to your product

What must become true

The signup form asks only for what the account cannot exist without, normally an email address, and anything else is asked after the first result.

Where it usually lives

The signup form and the handler behind it. Later fields move to the first-run screen or the account settings.

The trap

A field you stop asking for but still require in the handler or the database breaks signup for every visitor. Test a signup with only the required fields.