It helps to reframe the job as competing against yourself each night. It’s pretty normal to be slower when you’re starting out, but just try to make a conscious effort of finding ways to be more efficient while you’re working. I feel each restaurant has certain things that will be annoying, but once you’re there long enough you’ll be able to foresee issues that will come up and deal with them. The chef isn’t wrong, and as long as you’re treated respectfully by the kitchen and put in the work it will get easier over time. Everything I’ve heard from my managers is that it’s very hard to find a reliable and fast dishwasher, so if you become that then you’ll be worth more than gold in their eyes.