From the article:
Queries and joins are bad for your website performance. So is connecting to a database in the first place.
When I read this I thought of a quote a friend of mine made: "We put the 'DUH' in 'datacenter'." Kinda like the difference between (to borrow the author's waiter analogy) pulling leftovers from the fridge vs a full seven-course meal at an exclusive restaurant. "DUH", it's tons faster to pull from the fridge, but you might not want to eat it depending upon how long it's been there.
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Just my $0.02 from over here in the cheap seats of the peanut gallery - please adjust for inflation and/or your local currency.