Most developers wait until performance becomes a problem before doing anything about it. By then, you're firefighting instead of building. Here are the optimizations you should implement from day one - they cost almost nothing upfront but save you from major headaches later.
Database & Queries
Add indexes on columns you query frequently. Your database has to scan every row without them, and that gets slower as your data grows.
Select only what you need. SELECT * pulls data you don't use, wastes bandwidth, and makes your queries slower.
Avoid N+1 queries. If you're fetching data in a loop, you're probably making one database call per iteration when you could make just one.
Paginate early. Don't wait until you have thousands of records to add pagination. Implement it when you have ten.
Caching Strategy
Cache what's unavoidably complex. If a query or request takes time and the result doesn't change often, cache it. Don't cache just because you can.
Use a CDN for static assets. Images, CSS, and JavaScript files should be served from edge locations close to your users, not from your application server.
Network & Infrastructure
Put your application close to users. Deploy to regions where your users are - latency matters more than most developers think.
Put services close to each other. If your API and database are in different regions, every request crosses continents unnecessarily.
Fail fast. Set appropriate timeouts so slow operations don't block everything else. If something's going to fail, let it fail quickly.
Application Architecture
Process heavy work asynchronously. Sending emails, generating reports, or processing uploads shouldn't happen in the request-response cycle—use queues.
Measure before you optimize. You can't fix what you don't measure. Track response times and error rates from day one.
These aren't premature optimization. They're sensible defaults that prevent problems before they start.
The time to implement them is now, when your application is small and changes are easy. Trying to retrofit them into a large codebase under production load is significantly harder.
Do it right from the start, and you won't have to do it again later.