Ever lost hours chasing a slow function or a flaky feature? Code optimization doesn’t have to be guesswork. Start by measuring, then fix the biggest wins first. Small, focused changes often save more time than sweeping rewrites.
First rule: profile before you optimize. Use a profiler (like pyinstrument for Python, Chrome DevTools for JS, or perf for native apps) and find the hotspots. If a function runs in 40% of the time, that’s your target. Don’t waste time on parts that hardly run.
Replace repeated work with cached results. If a function computes the same value from the same inputs, memoize it. For web apps, cache query results or rendered fragments instead of rebuilding them on every request. Simple in-memory caches or Redis often cut response time dramatically.
Fix slow algorithms, not just code style. A faster algorithm (O(n log n) vs O(n^2)) can beat micro-optimizations every time. Before tweaking loops and allocations, check whether a better approach exists: sorting, hashing, or batching calls instead of singletons.
Reduce I/O waits. Disk and network calls are slow. Batch database queries, add indexes where queries scan many rows, and use asynchronous calls when waiting is unavoidable. For file-heavy tasks, stream data instead of loading everything into memory.
Keep functions small and focused. Small functions are easier to test and to profile. Inline only when it speeds up a tight loop and after you measured the benefit. Use clear names and avoid deep nesting; readability helps you spot bottlenecks faster.
Use types and lightweight checks to avoid hidden costs. In dynamically typed languages, add type hints and use tools that optimize based on them. In compiled languages, pay attention to allocation patterns—reducing allocations in hot paths usually improves throughput.
Automate performance checks. Add a few realistic benchmarks to CI so you catch regressions early. A 5% slowdown introduced today can become a major pain in production. Track key metrics: latency p95, memory usage, and throughput, not just averages.
Don’t forget debugging and testing. Reproduce slow cases locally with the same inputs. Add logging that helps you trace expensive operations without spamming production. When you fix a bug, write a test that prevents regressions.
Final shortcuts: use language and framework tools that fit your use case. For CPU-heavy tasks, compiled languages or optimized libraries help. For I/O-bound apps, async frameworks and connection pooling matter more. Make trade-offs explicit and measure the impact.
Want a quick checklist? Profile first, target hotspots, pick better algorithms, reduce I/O, cache smartly, test and benchmark, and add automated checks. Follow those steps and you’ll cut real time off your app without wasting hours on guesswork.