Which country has the fastest processing time for the DTV visa application: Laos, Cambodia, or Vietnam?

I applied on 17th April, first working day after Pi Mai (Lao Songkran). There were very few people in the payment queue. Recieved invitation for interview same day. 18th April 9:30 went to interview. They asked me about my work (I applied with workcation category), mostly facts from documents I attached (like when I started working, where the company is located, where did I work before). It looked like they wanted to tell if I cheated in my application documents or not (I didn't, so answered all their questions easily). Finally, they asked me to show my banking app, checked the account name, the amount of money, recent transactions. The interview was very friendly and polite. If you don't cheat you have nothing at all to worry about. From my point of view the interview is even better than to just submit online, because during the talk you have better chance to convience officer that you qualify for this visa. After interview I got email with visa within 15 minutes.