To any experienced Python dev, it's obvious from their description of what the problem is. And it's understandable that anyone inexperienced with Python would blame Python.
They were returning a large number of rows from Postgres (which, if the DB is properly set up, should take at most tens of ms: of course, depending on the width of the rows too), and most (well, I know of none that don't) Python ORM libraries (SQLAlchemy included) have a huge "serialization" cost (turning raw data from Postgres into objects). I've done a benchmark once, and things like Django-ORM or SQLAlchemy were like 10-50x slower than fetching tuples with psycopg directly. SQLAlchemy-core was fastest when fetching tuples if you wanted to not do raw SQL (IIRC, a performance penalty of at most 100%, translated to a factor, up to 2x slower), but Django's fetch-me-tuples functionality was also a single digit multiple of psycopg.
So, the solution to that problem is to fetch tuples, and then pass them in for rendering the page.
Of course, this also points at the problem with all the ORM implementations in Python: they are being too "smart" and dynamic for their own good (if all are bad at it, it also means that Python is not doing something good either, so criticism is warranted).