Every few months someone declares Rails dead. Then Shopify reports another record Black Friday. In 2025, Shopify's Rails monolith handled 489 million requests per minute at peak with over 53 million database queries per second. That's not a framework that fails to scale Ruby on Rails . But the "Rails can't scale" myth keeps coming back because the Ruby on Rails scalability issues people hit in production are real. They just aren't framework problems. They're architecture and discipline problems. Here's what we kept hitting in our own apps and what actually worked. N+1 Queries Quietly Kill Your Database This one shows up early and silently. You loop through 100 posts and call post.author.name , and ActiveRecord fires 101 queries. The page feels fine in dev with 5 records. In production with 50,000, it falls over. Slow queries are the most common Ruby on Rails scalability issues we see when auditing older codebases.…