If a buyer sends a risky payment option such as PayPal, they get reviewed for safety. Most of the time, the system does that in seconds and passes the transaction. The company checks safety so carefully that they can guarantee sellers always get paid. Being that bulletproof takes time and effort if something goes in to manual review processes.
For example:
If that same buyer has no credit history, no employment history, never rented a house or owned a car, has no verifiable address, isn't found in the phonebook, etc. That can slow things down considerably and the company might be left with no option but to ask for ID.
But then there can be even more complexity such as: does the buyer have a digital camera, a scanner, or will they walk to a fax machine? First, are they even available to answer the call or check their mail. Maybe they placed their order and then went to a rave and won't be back for 12 hours. That sounds funny, but it happens. That's why we have processes for painless order cancellation if something ever gets stalled for any reason.
PlayerAuctions generally goes just as fast as the buyer goes. The important thing to remember is that this is simply the speed of safety.
Waiting for the verification check shouldn't be screwing up your delivery speed rating because the clock should only start after verification is done and you get the "go" signal for safe trade.
If that's not the case for some reason, let me know and I will get that updated.