I formerly worked for a travel company. It was the best codebase I've ever inherited, but even so there were select N+1's everywhere and page loads of 2+ seconds were common. I gradually migrated most of the customer-facing pages to use hand-written SQL and Dapper; getting most page loads below 0.5 seconds.

The resulting codebase was about 50kloc of C# and 10kloc of SQL, plus some cshtml and javascript of course. Sounds small, but it did a lot -- it contained a small CMS, a small CRM, a booking management system that paid commissions to travel agents and payments to tour operators in their local currencies, plus all sorts of other business logic that accumulates in 15+ years of operation. But because it was a monolith, it was simple and a pleasure to maintain.

That said, SQL is an objectively terrible language. It just so happens that it's typically the least of all the available evils.