Query planning seems like it should be the topic of the article. SQLite and PostgreSQL do their query planning very differently - not to mention that SQLAlchemy is probably generating different queries. I can't really fathom how one can meaningfully "evaluate the two databases head to head" while seeming to actively avoid how they plan/optimize/execute queries.
I don't have access to the code used in the article. Therefore, no amount of research on my part is capable of answering why PostgreSQL was faster than SQLite in the author's situation - certainly not without the queries and the plans / EXPLAINs thereof, those being the specific thing I and multiple others have suggested as something the article could've provided and which would've made it an actually interesting head-to-head.
Meanwhile, if all you have to offer in response to such a suggestion is "hurr durr do it yourself", then why bother commenting at all?
Query planning seems like it should be the topic of the article. SQLite and PostgreSQL do their query planning very differently - not to mention that SQLAlchemy is probably generating different queries. I can't really fathom how one can meaningfully "evaluate the two databases head to head" while seeming to actively avoid how they plan/optimize/execute queries.