How to optimize application performance — a hands on tutorial

Performance Optimization: Measure Before You Optimize

Donald Knuth's famous warning-"premature optimization is the root of all evil"-boils down to one principle: measure before optimizing . Without real-world evidence that your application is too slow, you're guessing where to fix problems, and guesses create the wrong solutions.

The Golden Rule: Establish a Baseline First

Before touching any code, establish baseline metrics:

Load time (FCP, LCP, TTI)

Bundle size

Query durations

Memory usage

CPU utilization

Profile the system to locate hot spots, identify root causes, then apply one targeted optimization at a time . After each change, re-measure and document the impact.

Using Profilers to Identify Bottlenecks

How Profilers Work

Performance profilers measure how long routines take to execute, how often they're called, where they're called from, and what percentage of total time is spent there.…