How I Would Fix slow pages and weak Core Web Vitals in a React Native and Expo founder landing page Using Launch Ready.

How I Would Fix slow pages and weak Core Web Vitals in a React Native and Expo founder landing page Using Launch Ready

The symptom is usually simple: the page feels heavy, the hero takes too long to appear, buttons shift after load, and mobile users bounce before they ever see the CTA. In business terms, that means weaker conversion, worse ad efficiency, and a landing page that looks unfinished even if the product itself is good.

The most likely root cause is not one thing. It is usually a mix of oversized images, too many third-party scripts, unnecessary client-side rendering, and poor deployment hygiene around caching and assets.

If I were inspecting this first, I would start with the production URL in Lighthouse and WebPageTest, then check what Expo is actually shipping, what Cloudflare is caching, and whether the page is loading secrets or analytics in a way that slows first paint. For a founder landing page, I care less about code elegance and more about whether the page loads fast on a mid-range phone over 4G.

Triage in the First Hour

1. Open the live page on mobile with Chrome DevTools remote debugging. 2. Run Lighthouse for mobile and record:

• LCP
• CLS
• INP
• Total blocking time
• JS bundle size

3. Check the waterfall in WebPageTest or PageSpeed Insights. 4. Inspect the Expo build output:

• Are images bundled correctly?
• Is any screen doing heavy work on initial render?
• Are fonts blocking text paint?

5. Review Cloudflare settings:

• Cache rules
• Compression
• Redirects
• SSL mode
• Page rules or transform rules

6. Check DNS and domain setup:

• Correct A/CNAME records
• No redirect loops
• No mixed content warnings

7. Review analytics and tag scripts:

• GTM
• Meta Pixel
• Hotjar
• Any chatbot or widget script

8. Inspect browser console for:

• Hydration warnings
• JS errors
• Failed image requests

9. Confirm environment variables are not exposing anything sensitive in client code. 10. Verify uptime monitoring is enabled so we know if changes break production.

A quick diagnostic command I would use on the deployed site:

npx lighthouse https://your-domain.com \
  --preset=mobile \
  --only-categories=performance \
  --output=json \
  --output-path=./lighthouse-report.json

For a founder landing page, my target after cleanup is usually:

• LCP under 2.5s on mobile
• CLS under 0.1
• INP under 200ms
• Lighthouse performance score above 85 on mobile

Root Causes

| Likely cause | How I confirm it | Business impact | | --- | --- | --- | | Oversized hero images or video | Waterfall shows large asset transfer before first render | Slow first impression, high bounce rate | | Too much client-side rendering | Long JS execution, delayed text paint, hydration warnings | Weak LCP and sluggish interaction | | Third-party scripts loaded too early | Performance trace shows blocking network calls from analytics/widgets | Higher latency and more failure points | | Fonts not optimized | FOIT/FOUT visible, font files load late | Layout shift and ugly initial render | | Bad caching or no CDN tuning | Repeat visits still download too much | Wasted bandwidth and slower return visits | | Domain or redirect misconfiguration | Extra hops, redirect loops, mixed content | Delays launch and breaks trust |

For React Native plus Expo landing pages, I often find the same pattern: the team used app-style patterns for a web-first marketing page. That works for demos but hurts Core Web Vitals when you need fast acquisition pages.

The Fix Plan

I would fix this in a strict order so we improve speed without breaking tracking or launch flow.

1. Reduce what loads before first paint.

• Remove non-essential widgets from the landing page shell.
• Delay chat widgets, heatmaps, review embeds, and secondary analytics until after interaction or consent.
• Keep one primary analytics tool only if possible.

2. Optimize images aggressively.

• Convert hero visuals to WebP or AVIF.
• Resize images to actual display dimensions.
• Serve responsive sizes instead of one large asset.
• Avoid autoplay video unless it directly improves conversion.

3. Make the above-the-fold section static where possible.

• Render headline, subheadline, CTA, and trust markers as early as possible.
• Avoid waiting on API calls just to show core marketing content.
• If data is needed, cache it at build time or serve it from static JSON.

4. Fix fonts and layout stability.

• Use one or two font families max.
• Preload only the font weights actually used above the fold.
• Set explicit width and height for images to stop layout shift.
• Reserve space for banners and cookie notices.

5. Tune Expo web output for performance.

• Remove dead dependencies from shared app code that do not belong on web.
• Split marketing-page components from product-app components if they share a repo.
• Ensure no heavy native-only logic leaks into web bundles.

6. Put Cloudflare in front of static assets properly.

• Cache static files at edge.
• Enable compression.
• Use long cache headers for fingerprinted assets.
• Turn on DDoS protection and SSL correctly so trust signals do not fail at load time.

7. Clean up redirects and domain behavior.

• Force one canonical domain only.

For example: apex to www or www to apex, not both ways. Keep HTTPS everywhere. Remove chains longer than one hop where possible.

8. Secure the launch surface while improving speed.

Here is how I would think about the sequence:

The key trade-off is this: do not chase a perfect score by removing every script if that hurts attribution or lead capture. I would keep only what supports revenue tracking or trust-building on day one.

Regression Tests Before Redeploy

Before I ship anything back to production, I want proof that speed improved without breaking lead capture or security basics.

1. Mobile Lighthouse test passes with:

• Performance score at least 85
• LCP under 2.5s
• CLS under 0.1

2. Real-device smoke test on iPhone-sized viewport:

• Hero text visible quickly
• CTA clickable without delay
• No horizontal scroll

3. Network check:

• No unexpected third-party requests before user interaction
• Image payload reduced from baseline by at least 40 percent if images were oversized

4. Form test:

• Lead form submits successfully
• Validation messages are clear
• Success state appears once only

5. Security checks: If forms collect email addresses or phone numbers: remove exposed secrets from client code, confirm CSP does not block core assets, verify CORS is not overly open, confirm rate limiting exists on any submission endpoint, check SPF/DKIM/DMARC if email delivery matters.

6. Visual stability checks: No layout shift when fonts load, no banner overlap, no CTA movement after hydration.

7. Monitoring checks: Uptime monitor returns green, error logging works, deploy rollback path exists.

My acceptance criteria are simple: the page should feel fast on a real phone, should not jump around visually, should keep working after deploys, and should not expose sensitive configuration in source maps or public env vars.

Prevention

I would stop this coming back by putting guardrails around both code review and deployment.

• Performance budget:

Set a hard limit for initial JS bundle size and image payloads per page.

• Code review checklist:

Review behavior first: render cost, network calls, dependency bloat, secret handling.

• Security guardrails:

Keep secrets server-side only when possible; never ship private keys in Expo public config fields.

• Monitoring:

Track Core Web Vitals in production with alerts when LCP or CLS regresses after release.

• QA gate:

Every change touching landing pages gets a mobile performance smoke test before merge.

• UX guardrails:

Keep above-the-fold content focused on one job: explain value and get the click.

• Deployment discipline:

Use staging previews before production pushes so broken redirects or bad cache headers do not hit live traffic.

If I were doing this long term for a founder team using AI-built tooling like Expo plus external services around it (email delivery tools included), I would treat performance as part of launch readiness rather than an optional polish pass.

When to Use Launch Ready

Launch Ready fits when the landing page exists but is slowing down growth because deployment hygiene was never finished properly.

Use it if you need me to handle:

• Domain setup within 48 hours
• Email authentication so your outbound messages do not land in spam
• Cloudflare caching and DDoS protection
• SSL setup without redirect mistakes
• Production deployment with clean environment variables
• Secret handling so nothing sensitive ships to the browser
• Uptime monitoring so failures are visible fast

What you should prepare before booking is simple:

1. Domain registrar access. 2. Hosting or deployment access for Expo web output. 3. Cloudflare access if already connected. 4. Email provider access if your form sends leads by email. 5. A list of all third-party scripts currently running on the page. 6. The current repo or exported project files.

If your main problem is slow pages plus weak Core Web Vitals during launch week, I would fix infrastructure first instead of redesigning everything again. That keeps ad spend from leaking into a broken experience while giving you a cleaner base for later conversion work.

References

• https://roadmap.sh/frontend-performance-best-practices
• https://roadmap.sh/cyber-security
• https://roadmap.sh/code-review-best-practices
• https://developer.chrome.com/docs/lighthouse/performance/
• https://docs.expo.dev/guides/web/

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Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*