In-depth articles, tutorials, and guides on Performance — covering everything from fundamentals to advanced patterns.
A primary key is only the start. Real products need secondary indexes, covering indexes, multidimensional search, inverted indexes for text, and vector indexes for semantic similarity, each built around a different query shape.
Analytical systems are optimized for scanning huge histories, not serving tiny transactional lookups. That is why warehouses lean on columnar storage, aggressive compression, batched writes, vectorized execution, and precomputed aggregates.
Modern databases do not all store and retrieve data the same way. LSM-trees and B-trees make different bets on append-only writes, in-place updates, compaction, caching, and amplification, and those bets show up in latency, throughput, and operational behavior.
Performance is not one number. Response time, throughput, queueing, percentiles, retry storms, and SLOs all interact, which is why systems that seem fast in staging can collapse under real load.
Not all performance wins come from the same layer. Caches, CDNs, and database indexes all speed up reads, but they solve different bottlenecks and create different failure modes around staleness, invalidation, and query cost.
Memoization in React is a performance optimization, not a default behavior. But many codebases use useMemo and useCallback everywhere — creating overhead, obscuring intent, and sometimes preventing the optimizations they were meant to enable. Knowing when memoization helps and when it hurts is more important than knowing the API.
Memory leaks in UI applications are subtle and cumulative — they rarely cause an immediate crash but instead cause the application to slow down over time until the tab becomes unresponsive. Knowing where they come from and how to find them in DevTools is a critical skill for building long-lived browser applications.
Interaction to Next Paint replaced First Input Delay as a Core Web Vital in March 2024. Unlike FID, which measured only the delay before an interaction was handled, INP measures the full time from any interaction to the next paint — making it a far more accurate signal of real-world responsiveness.
Cumulative Layout Shift measures visual instability — the total amount of unexpected layout movement that occurs during a page's lifetime. A high CLS score means elements shift under the user's cursor right as they try to click. It is one of the most impactful Core Web Vitals for perceived quality.
Largest Contentful Paint is Google's primary metric for perceived load speed. It measures when the biggest visible content element finished rendering — and it is one of the most impactful Core Web Vitals for both user experience and search ranking.
Caching makes applications fast. Cache invalidation makes them correct. The challenge is not storing data — it is knowing when stored data is no longer fresh and deciding what to do about it. Every caching strategy is a trade-off between freshness, performance, and complexity.
MutationObserver is the standard API for watching DOM changes, but it is easy to create observers that fire far more often than expected and trigger expensive processing on every mutation. Understanding when and why it fires is essential for using it without tanking performance.
Traditional server-side rendering waits for all data to be fetched before sending any HTML. Streaming SSR changes this by sending HTML in chunks as it becomes ready, dramatically improving time to first byte and perceived performance for data-heavy pages.
Layout thrashing is one of the most common and most fixable causes of janky UIs. It happens when JavaScript forces the browser to repeatedly recalculate layout in a single frame — and it can turn a 60fps animation into a stuttering slideshow.
From the moment you type a URL to the moment pixels appear on screen, the browser executes a precise multi-stage pipeline. Understanding every stage — and what can interrupt each one — is the foundation for all frontend performance work.
Before a user sees anything on screen, the browser has to go through a precise sequence of steps. Understanding that sequence — the critical rendering path — is the foundation of every meaningful frontend performance optimization.
Understand the differences between default and named imports in React, when to use each, and how to leverage React’s lazy function for code-splitting. This guide provides practical examples and tips for using React.lazy with named exports to optimize your React application’s performance.
Memoization is an optimization technique used primarily to speed up computer programs by storing the results of expensive function calls and reusing them when the same inputs occur again. This article aims to provide a clear understanding of what memoization is and how to use it in JavaScript.