I was recently in a job interview (yes, the kind you have to do when you get laid off) and the interviewer asked me: "How would you scale a frontend application from 100,000 users to a million plus?"
I gave a decent enough answer at the moment. But afterwards, I kept thinking about everything I didn't say. So here we are. Consider this my full answer, delivered about three months too late, to actually matter for that job.
First, Let's Calibrate
Scaling a frontend isn't just about throwing more servers at the problem. That's your backend team's headache. The frontend has its own scaling concerns, and a lot of them are invisible until you're already on fire. The jump from 100k to 1M+ users is less about one dramatic architectural overhaul and more about fixing the 20% of things causing 80% of your slowness. The trick is knowing which 20%.
Performance & Asset Delivery: The Biggest Bang For Your Buck
