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.
1.49 s
Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.
2.16 s
Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.
4 ms
Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.
0.130
Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.
1.95 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.
2.62 s
Page Load Progression
FPage Weight BudgetAction3.2 MB transferred, 96 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
DJS BundlesAction33 scripts, 307 KB unusedFIX
Downloaded but never executed on this page.
| Script | Size | Unused | Minified | Party |
|---|---|---|---|---|
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604160201/pubads_impl.js | 188 KB | 107 KB (57%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtag/js?id=G-3XH4NJPYQ3&cx=c>m=4e64h1 | 159 KB | 63 KB (40%) | ✓ | 3rd |
| https://www.googletagmanager.com/gtm.js?id=GTM-NDXD39TW | 119 KB | 61 KB (52%) | ✓ | 3rd |
| https://h030.towardsdatascience.com/plugin/library/7cca1e1e3b698c80920cd851b1480f54 | 41 KB | 33 KB (81%) | ✓ | 3rd |
| https://h030.towardsdatascience.com/plugin/plugin/dd57986da60b4d6466f09420824e2e87 | 32 KB | 22 KB (70%) | ✓ | 3rd |
| https://cdn.insightmediagroup.io/imgjs/v1/imgjs-v1.js?ver=1776808444 | 28 KB | 21 KB (77%) | ✗ | 3rd |
| https://towardsdatascience.com/wp-content/plugins/ui-kit-navigation//dist/js/scroll-lock.js?ver=2.1.5 | 4 KB | — | ✓ | 1st |
| https://towardsdatascience.com/wp-content/themes/tds-theme/dist/js/frontend-module.js?ver=485fb0b9996654cbfa28 | 1 KB | — | ✓ | 1st |
| https://h030.towardsdatascience.com/script.js | 41 KB | — | ✓ | 3rd |
| https://scripts.simpleanalyticscdn.com/latest.js | 5 KB | — | ✓ | 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
DPage Weight InventoryAction96 resources · 3.2 MB · 307 KB savings availableFIX
~307.1 KiB of savings available
| # | Resource | Type | Size | Cache | Unused | 3rd party | Issues |
|---|---|---|---|---|---|---|---|
| — | — | ||||||
| 96 resources | 3.2 MiB | ||||||
BImage Optimization30 images, 0 KB saveableREVIEW
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
No green hosting detected
AThird-Party Impact25% third-party, 0 ms blockingPASS
A+Text CompressionAll text resources are compressedPASS
A+JS Execution Cost377ms total JS executionPASS
Main Thread Breakdown
| Script | Total | Scripting | Parse/Compile | Party |
|---|---|---|---|---|
| Unattributable | 139ms | 25ms | 0ms | 3rd |
| https://towardsdatascience.com/ | 137ms | 9ms | 1ms | 1st |
| https://securepubads.g.doubleclick.net/pagead/managed/js/gpt/m202604160201/pubads_impl.js | 101ms | 85ms | 11ms | 3rd |
A+Font Loading5 fonts (289 KB)PASS
Web fonts
5
289 KB total
Render-blocking
0
of 5
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
AHTTP Cachingmax-age=600 (10 minutes)PASS
max-age=600, must-revalidate
| Directive | Value | Meaning |
|---|---|---|
| max-age | 600 | Cache for 10 minutes |
| must-revalidate | — | Must recheck with server after expiry |
Network Waterfall96 requests over 3727msINFO
Third-Party Script CostPer-script blocking time, transfer cost, and cache headersINFO
| Script | Category | Execution | Transfer | Unused | Monthly Cost | Verdict |
|---|---|---|---|---|---|---|
Unattributable Unattributable | Other | 139ms | 0 KB | — | €2/mo | Optional |
securepubads.g.doubleclick.net securepubads.g.doubleclick.net | Other | 101ms | 188 KB | 57% | €1/mo | Optional |
64% 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
57% 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