It'd take you about 48 days :) When I checked that ID of the most recent user was 5663608. The github API will give you 5000 hits an hour if you authenticate y

It'd take you about 48 days :) When I checked that ID of the most recent user was 5663608. The github API will give you 5000 hits an hour if you authenticate your requests. You'd have a load of "not founds" but working up from 1 to 5663608 would get you every public user (no private accounts or banned / deleted). 5663608 / 5000 = just under 48 days worth of non stop API harrasment... maybe that explains why github keeps going down, someone is already trying this out :P