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Performance

· 25 checks — Lighthouse + waterfall + sustainability rolled into one auditable list.
SCORE
91
GRADE
A
FIX
1
REVIEW
8
PASS
14
INFO
2

Performance-focused optimization plan with CWV assessment, top offenders, and time estimates

Mobile Desktop
95
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
93
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
100
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

842 ms

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

1.11 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

248 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.000

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

842 ms

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

2.96 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 s
Checks
25
14 PASS 8 REVIEW 1 FIX
D
HTTP Caching
Action
No cache headers
FIX
No cache headers
Warning::
No Cache-Control header found
Browsers will use heuristic caching, which can be unpredictable. Set explicit cache headers.
Info::
ETag present — enables conditional (304) responses
Info::
Last-Modified header present

No Cache-Control header

Adding a Cache-Control header can significantly improve repeat-visit performance.

B
Third-Party Impact
54% third-party, 0 ms blocking
REVIEW
54% third-party, 0 ms blocking
Warning::
Third-party code accounts for 54% of page weight (157.7 KiB of 291.1 KiB)
Info::
Third-party blocking time is low (0 ms)
46%
54%
First-party Third-party
B
JS Execution Cost
958ms total JS execution
REVIEW
958ms total JS execution
Warning::
https://www.googletagmanager.com/gtag/js?id=G-QZL8...: 349ms CPU time
Info::
https://zachbloss.com/: 214ms CPU time
Info::
https://zachbloss.com/_next/static/chunks/117-fd9a...: 143ms CPU time
Info::
https://zachbloss.com/_next/static/chunks/fd9d1056...: 127ms CPU time
Info::
Unattributable: 125ms CPU time
Info::
Third-party scripts: 474ms (49% of total)

Main Thread Breakdown

Script Evaluation 51% Other 20% Style & Layout 15% Script Parsing & Compilation 11%
ScriptTotalScriptingParse/CompileParty
https://www.googletagmanager.com/gtag/js?id=G-QZL88MYQ0R349ms281ms62ms3rd
https://zachbloss.com/214ms5ms3ms1st
https://zachbloss.com/_next/static/chunks/117-fd9a974b596ffbc5.js143ms108ms18ms1st
https://zachbloss.com/_next/static/chunks/fd9d1056-317b731b1341f34f.js127ms83ms20ms1st
Unattributable125ms7ms0ms3rd
B
JS Bundles
11 scripts, 84 KB unused
REVIEW
11 scripts, 84 KB unused
Warning::
https://www.googletagmanager.com/gtag/js?id=G-QZL8...: 64 KB unused (41%)
Consider code splitting or tree shaking to reduce unused code.
Warning::
https://zachbloss.com/_next/static/chunks/fd9d1056...: 20 KB unused (40%)
Consider code splitting or tree shaking to reduce unused code.
Info::
Total unused JavaScript: 84 KB
84 KB unused JavaScript

Downloaded but never executed on this page.

ScriptSizeUnusedMinifiedParty
https://www.googletagmanager.com/gtag/js?id=G-QZL88MYQ0R157 KB64 KB (41%)✓3rd
https://zachbloss.com/_next/static/chunks/fd9d1056-317b731b1341f34f.js51 KB20 KB (40%)✓1st
https://zachbloss.com/_next/static/chunks/webpack-fdd2a341866a0d74.js2 KB—✓1st
https://zachbloss.com/_next/static/chunks/117-fd9a974b596ffbc5.js30 KB—✓1st
https://zachbloss.com/_next/static/chunks/main-app-a6721b193a74dd02.js1 KB—✓1st
https://zachbloss.com/_next/static/chunks/103-c8ef02e8fc511e64.js4 KB—✓1st
https://zachbloss.com/_next/static/chunks/app/page-6756a5995fafed23.js1 KB—✓1st
https://zachbloss.com/_next/static/chunks/965-6189fad9efafd3c5.js9 KB—✓1st
https://zachbloss.com/_next/static/chunks/309-e74571308ab80e08.js8 KB—✓1st
https://zachbloss.com/_next/static/chunks/app/not-found-b46a909cc987f035.js1 KB—✓1st

Consider code splitting or tree shaking to reduce unused code.

Why this matters

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.

Why this matters

This bundle has high unused code — code-split or tree-shake to ship only what executes.

Source: web.dev / Lighthouse coverage

B
HTTP/3 (QUIC)
HTTP/3 not advertised
REVIEW
HTTP/3 not advertised
Info::
HTTP/3 (QUIC) is not advertised
HTTP/3 isn't advertised via Alt-Svc and the worker didn't negotiate h3. HTTP/3 reduces handshake latency (1-RTT instead of 2-3 RTTs) and is more resilient on lossy connections. Most modern CDNs (Cloudflare, Fastly, AWS CloudFront, Google Cloud CDN) support HTTP/3 with a single config switch -- consider enabling for mobile-heavy workloads.
C
Compression Algorithm
Action
Main response served uncompressed
REVIEW
Main response served uncompressed
Info::
Main HTML response has no Content-Encoding (uncompressed)
The main HTML document is served without compression. The Text Compression section above lists the broader picture; for the main response specifically, even gzip would shave ~70-80% off most text payloads.
B
Main HTML Cache-Control
No Cache-Control header on main HTML response
REVIEW
No Cache-Control header on main HTML response
Info::
Main HTML response has no Cache-Control header
Without an explicit Cache-Control, browsers fall back to heuristic caching (~10% of Last-Modified age). Set `Cache-Control: no-cache` or `max-age=300` for HTML to control freshness explicitly -- prevents stale auth state and SPA shell drift.
B
Server-Timing Observability
No Server-Timing header found
REVIEW
No Server-Timing header found
Info::
No Server-Timing header found
Server-Timing exposes backend timing breakdowns to browser DevTools (e.g., `db: 45ms; render: 120ms; cache: 2ms`). Useful for diagnosing slow pages without backend log access. Most modern frameworks (Next.js, Cloudflare Workers, Fastly) emit it automatically; absence on a managed platform usually means telemetry headers are stripped at the edge.
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Page Weight Budget
291 KB transferred, 15 requests
PASS
291 KB transferred, 15 requests
Info::
Page weighs 879 KB (291 KB transferred)
Info::
15 HTTP requests
Info::
Estimated 0.06 g CO2 per page load
291 KB / 2.4 MB budget
291 KB transferred
15 requests
0.06 g CO2 per page load
JavaScript 267.0 KiB 92%
Other 15.4 KiB 5%
CSS 5.3 KiB 2%
HTML 2.8 KiB 1%
Other 547 B 0%
0 2.4 MB 4.9 MB
Under budget
A+
Text Compression
All text resources are compressed
PASS
All text resources are compressed
Info::
All text resources are compressed
All text resources are properly compressed.
A+
Image Optimization
No images on this page
PASS
No images on this page
Info::
No images on this page
0 images 0 KB
0 oversized -0 KB
0 legacy format
0 missing dimensions CLS risk
A+
Font Loading
No web fonts (system fonts)
PASS
No web fonts (system fonts)
Info::
No web fonts loaded — system fonts are fastest
No web fonts loaded — system fonts are optimal.
A+
Resource Caching
All resources properly cached
PASS
All resources properly cached
Info::
No caching issues found
All static resources have appropriate caching headers.
A+
Critical Rendering Path
No render-blocking resources
PASS
No render-blocking resources
Info::
No render-blocking resources detected
A+
Resource Hints
2 hints, 0 missing preconnects
PASS
2 hints, 0 missing preconnects
Info::
Page uses 2 resource hint(s)

Current Resource Hints

preconnect
—
preload
2
dns-prefetch
—
prefetch
—

2 resource hints configured

A+
LCP Image Preload
LCP preload audit not available
PASS
LCP preload audit not available
Info::
LCP image preload audit not available for this scan
A+
Server Response Intelligence
2 server-response signal(s) detected
PASS
2 server-response signal(s) detected
Info::
`Vary` header declared: Accept-Encoding
The page declares a `Vary` header, telling downstream caches which request headers the response varies on. Critical for content-negotiated responses (compression, language, cookies, device class).
Info::
Both `ETag` and `Last-Modified` present -- efficient revalidation supported
The page returns both `ETag` (content hash) and `Last-Modified` (timestamp) headers. Browsers can issue conditional GETs with `If-None-Match` or `If-Modified-Since`; the server returns 304 Not Modified for unchanged content, saving bandwidth. ETag is the more reliable of the two (timestamps fail in DST transitions and clock skew).
A
Page Weight Inventory
15 resources · 291 KB · 84 KB savings available
PASS
15 resources · 291 KB · 84 KB savings available
Info::
Within 1MB page-weight target
Got: 291 KB
Info::
~84 KB of savings available
Warning::
2 third-party resources (54% of weight)
15 resources · 291.1 KiB · 2 third-party Within 1MB page-weight target
JavaScript 92% · 267.0 KiB
Image 5% · 15.4 KiB
CSS 2% · 5.3 KiB
Document 1% · 2.8 KiB
Other 0% · 547 B

~84.5 KiB of savings available

Remove unused JavaScript: 84.5 KiB
A+
Render-Blocking Resources
No render-blocking resources detected
PASS
No render-blocking resources detected
Info::
No render-blocking resources detected in <head>
A+
Third-Party Resources
No third-party resources detected
PASS
No third-party resources detected
A
JavaScript Blocking
1 JS blocking issue(s) detected
PASS
1 JS blocking issue(s) detected
Warning::
2 render-blocking <script src> tag(s) without async/defer
Each `<script src=...>` without `async`, `defer`, or `type="module"` blocks HTML parsing while the browser fetches and executes it. The block lasts the entire round-trip + execution time -- on slow networks this translates directly into LCP delay. Add `defer` (executes after parse, in source order) for scripts that interact with the DOM, or `async` (executes whenever ready) for analytics / independent scripts. Module scripts (`type="module"`) are deferred by default.
A+
CSS Performance Depth
No CSS performance depth issues detected
PASS
No CSS performance depth issues detected
Info::
No CSS performance depth issues detected
Network Waterfall
15 requests over 386ms
INFO
0 ms 500 ms 1.0 s FCP 842 ms LCP 1.1 shttps://zachbloss.com// https://zachbloss.com/ — 200 — 2.8 KiB — 107 ms — h2https://zachbloss.com/_next/static/css/97a0b82372a112fe.css/_next/static/css/97a0b82372a112fe.... https://zachbloss.com/_next/static/css/97a0b82372a112fe.css — 200 — 5.3 KiB — 16 ms — h2https://zachbloss.com/_next/static/chunks/webpack-fdd2a341866a0d74.js/_next/static/chunks/webpack-fdd2a3... https://zachbloss.com/_next/static/chunks/webpack-fdd2a341866a0d74.js — 200 — 2.1 KiB — 17 ms — h2https://www.googletagmanager.com/gtag/js?id=G-QZL88MYQ0Rwww.googletagmanager.com/gtag/js?id... https://www.googletagmanager.com/gtag/js?id=G-QZL88MYQ0R — 200 — 157.2 KiB — 124 ms — h2https://zachbloss.com/_next/static/chunks/fd9d1056-317b731b1341f34f.js/_next/static/chunks/fd9d1056-317b7... https://zachbloss.com/_next/static/chunks/fd9d1056-317b731b1341f34f.js — 200 — 50.5 KiB — 32 ms — h2https://zachbloss.com/_next/static/chunks/117-fd9a974b596ffbc5.js/_next/static/chunks/117-fd9a974b59... https://zachbloss.com/_next/static/chunks/117-fd9a974b596ffbc5.js — 200 — 30.5 KiB — 22 ms — h2https://zachbloss.com/_next/static/chunks/main-app-a6721b193a74dd02.js/_next/static/chunks/main-app-a6721... https://zachbloss.com/_next/static/chunks/main-app-a6721b193a74dd02.js — 200 — 818 B — 20 ms — h2https://zachbloss.com/_next/static/chunks/103-c8ef02e8fc511e64.js/_next/static/chunks/103-c8ef02e8fc... https://zachbloss.com/_next/static/chunks/103-c8ef02e8fc511e64.js — 200 — 3.5 KiB — 22 ms — h2https://zachbloss.com/_next/static/chunks/app/page-6756a5995fafed23.js/_next/static/chunks/app/page-6756a... https://zachbloss.com/_next/static/chunks/app/page-6756a5995fafed23.js — 200 — 1.0 KiB — 15 ms — h2https://zachbloss.com/_next/static/chunks/965-6189fad9efafd3c5.js/_next/static/chunks/965-6189fad9ef... https://zachbloss.com/_next/static/chunks/965-6189fad9efafd3c5.js — 200 — 8.7 KiB — 23 ms — h2https://zachbloss.com/_next/static/chunks/309-e74571308ab80e08.js/_next/static/chunks/309-e74571308a... https://zachbloss.com/_next/static/chunks/309-e74571308ab80e08.js — 200 — 7.7 KiB — 138 ms — h2https://zachbloss.com/_next/static/chunks/app/not-found-b46a909cc987f035.js/_next/static/chunks/app/not-found-... https://zachbloss.com/_next/static/chunks/app/not-found-b46a909cc987f035.js — 200 — 1.3 KiB — 24 ms — h2https://zachbloss.com/_next/static/chunks/app/layout-72f7127fb8b79338.js/_next/static/chunks/app/layout-72f... https://zachbloss.com/_next/static/chunks/app/layout-72f7127fb8b79338.js — 200 — 3.8 KiB — 26 ms — h2https://www.google-analytics.com/g/collect?v=2&tid=G-QZL88MYQ0R&gtm=45je6562v9196229803za200zd9196229803&_p=1778416601276&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=2126375899.1778416601&frm=0&pscdl=noapi&rcb=0&sr=412x823&uaa=&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~118463261~118719171&sid=1778416601&sct=1&seg=0&dl=https%3A%2F%2Fzachbloss.com%2F&dt=Zach%20Bloss%20Portfolio&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=339www.google-analytics.com/g/collect?... https://www.google-analytics.com/g/collect?v=2&tid=G-QZL88MYQ0R&gtm=45je6562v9196229803za200zd9196229803&_p=1778416601276&gcd=13l3l3l3l1l1&npa=0&dma=0&are=1&cid=2126375899.1778416601&frm=0&pscdl=noapi&rcb=0&sr=412x823&uaa=&uab=64&uafvl=Not-A.Brand%3B24.0.0.0%7CChromium%3B146.0.7680.164&uam=moto%20g%20power%20(2022)&uamb=1&uap=Android&uapv=11.0&uaw=0&ul=en-us&_s=1&tag_exp=0~115616986~115938465~115938469~118463261~118719171&sid=1778416601&sct=1&seg=0&dl=https%3A%2F%2Fzachbloss.com%2F&dt=Zach%20Bloss%20Portfolio&en=page_view&_fv=1&_nsi=1&_ss=1&_ee=1&tfd=339 — 204 — 547 B — 46 ms — h2https://zachbloss.com/favicon.ico/favicon.ico https://zachbloss.com/favicon.ico — 200 — 15.4 KiB — 12 ms — h2
HTML JavaScript CSS Images Fonts XHR/Fetch Other
Third-Party Script Cost
Per-script blocking time, transfer cost, and cache headers
INFO
49% of JavaScript execution is third-party
First-party Third-party 474ms · 157KB · $6/mo
Google Tag Manager
Tag Manager
Costly
Execution 349ms
Transfer 157 KB
Unused 41%
Monthly Cost $5/mo
Unattributable
Other
Optional
Execution 125ms
Transfer 0 KB
Monthly Cost $2/mo

These scripts may cost more than they're worth

  • Google Tag Manager adds 349ms and costs ~$5/month

49% of JavaScript execution time comes from third-party scripts.

Why this matters

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

Google Tag Manager takes 349ms of CPU time. Consider loading it asynchronously or replacing it with a lighter alternative.

Why this matters

This script has high main-thread execution time — optimize hot paths or defer.

Source: web.dev

How third-party costs are calculated

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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