The waiter is tired.

1. Workload: The cold dish chef only needs to make cold dishes and can rest after finishing the work. The workload is small, while the waiters need to serve customers non-stop, which is a heavy workload.

2. Walking around: The cold dish chef only needs to make cold dishes in a fixed position and does not need to move around. The waiter needs to move back and forth to serve the customers, so the waiter is more tired.