Performance
Finding the slow thing, and the tools that show you where it hides.
Watch it animated → Interactive, click-through walkthroughs for Performance concepts.Basic
What "Performance" Even Means Performance is two different numbers (latency and throughput), the rule that you measure before you optimize, and the truth that 'fast enough' is defined by a requirement and by what users actually feel.
Big-O Without the Math Panic Big-O isn't a math exam - it's a simple way to ask 'when my data gets bigger, does the work get a little bigger, a lot bigger, or catastrophically bigger?' This guide gives you that intuition with zero proofs.
Lazy Loading Explained Why deferring work until it's actually needed is one of the cheapest performance wins available, and where it stops paying off.
Intermediate
Finding the Slow Thing (Profiling 101) A profiler watches your program run and tells you where the time actually goes, so you fix the real bottleneck instead of guessing. Learn to read a profile and a flame graph, then run the measure-change-remeasure loop.
Observability: Logs, Metrics & Traces What observability actually is, how logs, metrics, and traces each see a different slice of your running system, and how to use all three together to find out why something is slow.
Reading Dynatrace (What It's Showing You) What Dynatrace actually is, how to follow one request through a distributed trace, and how to read a 'Problem' and its proposed root cause without trusting it blindly.
Reading Graylog (Log Search & Streams) What centralized logging actually is, how to search across dozens of servers from one box, and how streams, dashboards, and alerts turn a flood of logs into something you can stand on.
Prometheus & Grafana, Explained Prometheus scrapes and stores your metrics; Grafana queries and draws them. What each one actually does, how to read a PromQL query, and how to build dashboards and alerts that don't lie to you.
Web Performance and Core Web Vitals What actually makes a page feel fast: LCP, CLS, and INP, the Network tab and bundle size, and the fixes that move the numbers.
Memoization Explained How caching a pure function's return value by its arguments lets you skip redoing the same expensive work twice, and where that trick quietly breaks.
Debouncing and Throttling Two related techniques for taming a firehose of events - waiting for a pause versus capping the rate - and how to pick between them.
Advanced
Optimizing Real Systems Putting measurement to work end to end: run a disciplined optimization loop against a target, learn where the time actually goes in real systems, and ship speed safely in production without breaking correctness.