Performance
· 15 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.Performance-focused optimization plan with CWV assessment, top offenders, and time estimates
First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.
835 ms
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
2.22 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
457 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.456
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
1.21 s
Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.
5.76 s
Page Load Progression
375 ms
750 ms 1.1 s 1.5 s
1.9 s 2.2 s 2.6 s 3.0 sFPage Weight BudgetAction5.3 MB transferred, 133 requestsFIX
Large JavaScript bundles delay interactivity. Split code by route or defer non-critical scripts.
JavaScript bundle is large — code-split routes and lazy-load off-screen components to defer.
Source: web.dev
Convert images to WebP/AVIF and resize to display dimensions to reduce transfer size.
Image bandwidth is high — modern formats (WebP/AVIF) and resizing typically cut it 50%+.
Source: web.dev
Subset fonts to include only used characters, or switch to system font stacks.
Font payload is large — subset to used glyphs only, or fall back to system fonts (zero load time).
Source: web.dev font loading
Each request adds latency. Bundle small files, use sprites, or eliminate unnecessary requests.
High HTTP request count — bundling, sprite-ing, and HTTP/2 server push can reduce per-request overhead.
Source: web.dev
DThird-Party ImpactAction100% third-party, 0 ms blockingFIX
DJS Execution CostAction2342ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| https://try.abtasty.com/03d869a33f572dd77e62594449ebd8cb/main.4f8fe8525f40523c4a4c.js | 314ms | 278ms | 20ms | 3rd |
| https://www.tate.org.uk/ | 298ms | 5ms | 3ms | 3rd |
| Unattributable | 286ms | 10ms | 0ms | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 286ms | 235ms | 30ms | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-WQPJ9H | 269ms | 225ms | 22ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-4GZRWXM2P8&cx=c>m=4e64h1 | 119ms | 104ms | 14ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-Q4CTQC82D1&cx=c>m=4e64h1 | 115ms | 101ms | 13ms | 3rd |
| https://www.tate.org.uk/static/js/TateUI.c2ca8065327f.js | 106ms | 65ms | 13ms | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 96ms | 77ms | 18ms | 3rd |
| https://static.ads-twitter.com/uwt.js | 82ms | 65ms | 2ms | 3rd |
Showing top 10 of 16 scripts
FJS BundlesAction52 scripts, 1.2 MB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 0 KB | 177 KB (49%) | ✓ | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 362 KB | 177 KB (49%) | ✓ | 3rd |
| https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js | 362 KB | 177 KB (49%) | ✓ | 3rd |
| https://www.tate.org.uk/static/js/TateUI.c2ca8065327f.js | 138 KB | 79 KB (75%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-Q4CTQC82D1&cx=c>m=4e64h1 | 173 KB | 66 KB (38%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-4GZRWXM2P8&cx=c>m=4e64h1 | 155 KB | 61 KB (39%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=DC-13274131&cx=c>m=4e64h1 | 129 KB | 60 KB (46%) | ✓ | 3rd |
| https://analytics.tiktok.com/i18n/pixel/static/main.MWE0ZWQ3ZWQwMA.js | 106 KB | 57 KB (54%) | ✓ | 3rd |
| https://sdk.privacy-center.org/sdk/22ecd6bfac93de604efec0b75b2c796ee1675f92/modern/sdk.22ecd6bfac93de604efec0b75b2c796ee1675f92.js | 102 KB | 56 KB (54%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-1012661956&cx=c>m=4e64h1 | 145 KB | 55 KB (38%) | ✓ | 3rd |
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
Consider code splitting or tree shaking to reduce unused code.
This bundle has high unused code — code-split or tree-shake to ship only what executes.
Source: web.dev / Lighthouse coverage
FPage Weight InventoryAction133 resources · 5.3 MB · 1.2 MB savings availableFIX
~1.2 MiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 133 resources | 5.3 MiB | ||||||
CImage OptimizationAction41 images, 0 KB saveableREVIEW
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
Set explicit width and height to prevent CLS.
Image without explicit width/height — browser can't reserve space; CLS jumps when image loads.
Source: web.dev / Core Web Vitals
A+Text CompressionAll text resources are compressedPASS
A+Font Loading5 fonts (204 KB)PASS
Web fonts
5
204 KB total
Render-blocking
0
of 5
Dominant font-display
swap
Most common across fonts
Font loading timeline
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
- Convert to woff2 for ~30% smaller file size
Optimization checklist
- Preload critical fonts (priority=high)
- Use woff2 format for all fonts
- Set font-display to swap, optional, or fallback
- Subset large fonts (≤100 KB each)
Fixing the unchecked items could save ~51 KB and ~102 ms
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Axis12 Ltd
AHTTP Cachingmax-age=86400 (1 day)PASS
max-age=86400
| Directive | Value | Meaning |
|---|---|---|
| max-age | 86400 | Cache for 1 day |
Network Waterfall133 requests over 2907msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
try.abtasty.com try.abtasty.com | Other | 314ms | 67 KB | 62% | £3/mo | Costly |
www.tate.org.uk www.tate.org.uk | Other | 298ms | 15 KB | — | £3/mo | Costly |
Unattributable Unattributable | Other | 286ms | 0 KB | — | £3/mo | Costly |
www.gstatic.com www.gstatic.com | Other | 286ms | 0 KB | 49% | £3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 269ms | 206 KB | 26% | £3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 119ms | 155 KB | 39% | £1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 115ms | 173 KB | 38% | £1/mo | Optional |
www.tate.org.uk www.tate.org.uk | Other | 106ms | 138 KB | 75% | £1/mo | Optional |
analytics.tiktok.com analytics.tiktok.com | Other | 96ms | 106 KB | 54% | £1/mo | Optional |
Twitter/X Pixel static.ads-twitter.com | Advertising | 82ms | 13 KB | — | £1/mo | Optional |
ajax.googleapis.com ajax.googleapis.com | Other | 75ms | 30 KB | — | £1/mo | Optional |
sdk.privacy-center.org sdk.privacy-center.org | Other | 68ms | 102 KB | 54% | £1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 64ms | 145 KB | 37% | £1/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 61ms | 16 KB | — | £1/mo | Optional |
Facebook Pixel connect.facebook.net | Advertising | 53ms | 97 KB | 33% | £1/mo | Optional |
Hotjar script.hotjar.com | Session Replay | 51ms | 57 KB | 67% | £1/mo | Optional |
These scripts may cost more than they're worth
- try.abtasty.com adds 314ms and costs ~£3/month
- www.tate.org.uk adds 298ms and costs ~£3/month
- Unattributable adds 286ms and costs ~£3/month
- www.gstatic.com adds 286ms and costs ~£3/month
- Google Tag Manager adds 269ms and costs ~£3/month
100% of JavaScript execution time is spent on third-party scripts. Consider auditing which scripts are essential.
When third-party JS execution time exceeds your own, performance gains from frontend work are capped by code you don't own.
Learn more ▾ ▴
Every millisecond of third-party JS competes with your own for main-thread time. If their share is bigger than yours, optimization on your code base barely moves the needle. Audit, defer, or remove third-parties before further frontend optimization. Use Lighthouse's third-party audit to identify the worst offenders.
Source: web.dev
try.abtasty.com takes 314ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
62% of try.abtasty.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
www.tate.org.uk takes 298ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Unattributable takes 286ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
www.gstatic.com takes 286ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
Google Tag Manager takes 269ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.
This script has high main-thread execution time — optimize hot paths or defer.
Source: web.dev
75% of www.tate.org.uk's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
54% of analytics.tiktok.com's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
54% of sdk.privacy-center.org's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev
67% of Hotjar's code is unused. The script may be loading features you don't use.
Bundle has high unused-code ratio — tree-shaking and route-splitting recover the wasted bytes.
Source: web.dev