Performance · Definition
Browser cache
A browser's local storage of reusable web responses, governed by caching rules and validation behavior.
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20 definitions · Website glossary
Performance,
explained.
Understand loading, responsiveness, caching, measurement, and operational signals.
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Performance20
20 terms available
Performance · Definition
Cache
A store of reusable results or data that can reduce repeated retrieval or computation.
Understand the termPerformance · Definition
CDN
A content delivery network distributes delivery through geographically spread infrastructure that can cache or proxy content.
Understand the termPerformance · Definition
Compression
The reduction of data size using an encoding that a recipient can decode.
Understand the termPerformance · Definition
Core Web Vitals
A set of user-experience metrics covering loading, interaction responsiveness, and visual stability, currently LCP, INP, and CLS.
Understand the termPerformance · Definition
Cumulative Layout Shift
CLS measures unexpected visual movement of page elements using a session-window method.
Understand the termPerformance · Definition
Field data
Performance measurements collected from real visits in actual user environments.
Understand the termPerformance · Definition
First Contentful Paint
FCP marks when a browser first renders qualifying content from the page.
Understand the termPerformance · Definition
Interaction to Next Paint
INP assesses page responsiveness by examining the latency of qualifying interactions over a visit.
Understand the termPerformance · Definition
Lab data
Measurements collected in a controlled or simulated test environment.
Understand the termPerformance · Definition
Largest Contentful Paint
LCP reports when the largest eligible visible content element in the initial viewport is rendered.
Understand the termPerformance · Definition
Latency
The delay between initiating an operation and receiving a response or result.
Understand the termPerformance · Definition
Lazy loading
The deferral of nonessential resource loading until the resource is needed or near use.
Understand the termPerformance · Definition
Minification
The removal of unnecessary characters or other safe simplifications from source assets to reduce their size.
Understand the termPerformance · Definition
Monitoring
The ongoing collection and evaluation of signals used to understand a system's condition and detect problems.
Understand the termPerformance · Definition
Performance budget
A deliberately chosen limit or target used to guide and review a site's performance-related decisions.
Understand the termPerformance · Definition
Render blocking
The condition in which a resource or task delays the browser from rendering content.
Understand the termPerformance · Definition
Responsive images
Image markup that lets a browser select suitable sources for layout size, resolution, or art direction.
Understand the termPerformance · Definition
Time to First Byte
TTFB measures the time from a request's start until the first byte of its response arrives.
Understand the termPerformance · Definition
Uptime
The time or proportion of time a monitored system is considered available under a stated definition.
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Where should I start with the Performance glossary?
Start with the experience being measured, then distinguish network timing, rendering, interaction, and field evidence.
- Time to First Byte: TTFB measures the time from a request's start until the first byte of its response arrives.
- Largest Contentful Paint: LCP reports when the largest eligible visible content element in the initial viewport is rendered.
- Interaction to Next Paint: INP assesses page responsiveness by examining the latency of qualifying interactions over a visit.
Which terms help me interpret performance measurements?
- Lab data: Measurements collected in a controlled or simulated test environment.
- Field data: Performance measurements collected from real visits in actual user environments.
- Performance budget: A deliberately chosen limit or target used to guide and review a site's performance-related decisions.
Which practical guides build on the Performance terms?
- Create a useful website performance baseline: Measure representative pages and interactions under recorded conditions before selecting optimizations or comparing hosting changes.
- Keep a performance change log: Preserve the context behind optimization work so the team can tell which change was tested and whether the complete user experience improved.