Performance
· 17 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.
4.21 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
27.78 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
1.01 s
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.006
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
9.43 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.
28.92 s
Page Load Progression
415 ms
831 ms 1.2 s 1.7 s 2.1 s 2.5 s
2.9 s
3.3 sFPage Weight BudgetAction5.6 MB transferred, 194 requestsFIX
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
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
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 ImpactAction86% third-party, 0 ms blockingFIX
FJS Execution CostAction4823ms total JS executionFIX
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| Unattributable | 1361ms | 23ms | 0ms | 3rd |
| https://bookshop.org/_next/static/chunks/2117-a7c96d3f711e8b10.js | 793ms | 718ms | 17ms | 1st |
| https://cmp.osano.com/mbso9YM8zJ/5bf7eaf8-0636-48dc-b8de-072565a02b02/osano.js | 694ms | 595ms | 27ms | 3rd |
| https://bookshop.org/ | 489ms | 54ms | 52ms | 1st |
| https://bookshop.org/gtgbkshp/ | 228ms | 190ms | 38ms | 1st |
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604170101/pubads_impl.js?cb=31097963 | 211ms | 144ms | 57ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-PBC1NBK83Q&cx=c>m=4e64h1&fps=fc&gdev=dNzQzZD | 206ms | 169ms | 36ms | 3rd |
| https://static.fbot.me/friendbuy.js | 196ms | 155ms | 29ms | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-669349773&cx=c>m=4e64h1&fps=fc&gdev=dNzQzZD | 183ms | 151ms | 32ms | 3rd |
| https://bookshop.org/_next/static/chunks/fd9d1056-298733a1a5e2fe4a.js | 165ms | 136ms | 11ms | 1st |
Showing top 10 of 14 scripts
FJS BundlesAction50 scripts, 551 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604170101/pubads_impl.js?cb=31097963 | 187 KB | 144 KB (77%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-52VMX98 | 158 KB | 103 KB (65%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=AW-669349773&cx=c>m=4e64h1&fps=fc&gdev=dNzQzZD | 153 KB | 74 KB (48%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-PBC1NBK83Q&cx=c>m=4e64h1&fps=fc&gdev=dNzQzZD | 173 KB | 72 KB (42%) | ✓ | 3rd |
| https://bookshop.org/_next/static/chunks/9070-5dd99bc2aa85a519.js | 80 KB | 58 KB (72%) | ✓ | 1st |
| https://static.fbot.me/friendbuy.js | 100 KB | 46 KB (46%) | ✓ | 3rd |
| https://bookshop.org/_next/static/chunks/8193-f645ef97c581c990.js | 65 KB | 33 KB (54%) | ✓ | 1st |
| https://cmp.osano.com/mbso9YM8zJ/5bf7eaf8-0636-48dc-b8de-072565a02b02/osano.js | 70 KB | 21 KB (30%) | ✓ | 3rd |
| https://bookshop.org/_next/static/chunks/7700-e05a3009ba979315.js | 5 KB | — | ✓ | 1st |
| https://bookshop.org/_next/static/chunks/962-538ef42fa59a1f10.js | 3 KB | — | ✓ | 1st |
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 InventoryAction194 resources · 5.6 MB · 551 KB savings availableFIX
~550.8 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 194 resources | 5.6 MiB | ||||||
FHTTP CachingActionNo cache headersFIX
No Cache-Control header
Adding a Cache-Control header can significantly improve repeat-visit performance.
BImage Optimization112 images, 0 KB saveableREVIEW
A+Text CompressionAll text resources are compressedPASS
A+Font Loading7 fonts (290 KB)PASS
Web fonts
7
290 KB total
Render-blocking
0
of 7
Dominant font-display
swap
Most common across fonts
Font loading timeline
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)
A+Resource CachingAll resources properly cachedPASS
A+Critical Rendering PathNo render-blocking resourcesPASS
A+Resource HintsNo optimization neededPASS
A+Render-Blocking ResourcesNo render-blocking resources detectedPASS
A+Third-Party ResourcesNo third-party resources detectedPASS
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
Network Waterfall194 requests over 2873msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Unattributable Unattributable | Other | 1361ms | 0 KB | — | $18/mo | Costly |
cmp.osano.com cmp.osano.com | Other | 694ms | 70 KB | 30% | $9/mo | Costly |
securepubads.g.doubleclick.net securepubads.g.doubleclick.net | Other | 211ms | 187 KB | 77% | $3/mo | Costly |
Google Tag Manager www.googletagmanager.com | Tag Manager | 206ms | 173 KB | 42% | $3/mo | Costly |
static.fbot.me static.fbot.me | Other | 196ms | 100 KB | 46% | $3/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 183ms | 153 KB | 48% | $2/mo | Optional |
securepubads.g.doubleclick.net securepubads.g.doubleclick.net | Other | 67ms | 34 KB | — | $1/mo | Optional |
Google Tag Manager www.googletagmanager.com | Tag Manager | 54ms | 158 KB | 65% | $1/mo | Optional |
These scripts may cost more than they're worth
- Unattributable adds 1361ms and costs ~$18/month
- cmp.osano.com adds 694ms and costs ~$9/month
- securepubads.g.doubleclick.net adds 211ms and costs ~$3/month
- Google Tag Manager adds 206ms and costs ~$3/month
62% of JavaScript execution time comes from third-party scripts.
Third-party scripts (analytics, ads, social, A/B testing) often dominate execution time — every one is a perf-and-privacy tax.
Learn more ▾ ▴
Each third-party script is a black box: you don't control when it loads, what it executes, or how much it grows. They often account for a major share of total blocking time on average sites (HTTP Archive's Web Almanac documents the trend). Audit which ones you actually need, defer the rest, and use facade patterns (lite-youtube, lite-vimeo) for embedded media.
Source: web.dev / HTTP Archive Web Almanac
Unattributable takes 1361ms 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
cmp.osano.com takes 694ms 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
securepubads.g.doubleclick.net takes 211ms 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
77% of securepubads.g.doubleclick.net'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
Google Tag Manager takes 206ms 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
65% of Google Tag Manager'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