Funny and I had a similar real life experience with a hadoop cluster. I replaced a job that needed 10 machines with a few lines of C, some python and GNU parallel, which was perl I believe at the time. The process was taking over 24 hours on the cluster and became unworkable. I got it back to 2 hours on my slow Macbook air.

On Dask, it may not be super fast for very large data sets but it is sure easy to use.