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 the same: the page feels heavy, the hero takes too long to appear, buttons lag on mobile, and Lighthouse keeps flagging LCP, CLS, and INP. In founder terms, that means more bounce, weaker conversion, and paid traffic leaking money before the first scroll.

The most likely root cause is not "one bad component." It is usually a mix of oversized images, too much JS on the first load, third-party scripts blocking render, weak caching, and a deployment setup that was never tuned for production. The first thing I would inspect is the actual route that visitors hit first: the landing page bundle size, network waterfall, image delivery, and whether Cloudflare and caching are configured correctly.

Launch Ready is the sprint I would use here if you need this cleaned up fast.

Triage in the First Hour

1. Open the live landing page on mobile throttling in Chrome DevTools. 2. Run Lighthouse for mobile only and record:

• LCP
• CLS
• INP
• Total Blocking Time

3. Check the network waterfall for:

• Largest image
• JS bundle size
• Font loading
• Third-party scripts

4. Inspect Expo build output and hosting logs for:

• Build warnings
• Asset paths
• Cache headers
• Redirect loops

5. Review the source files that control the homepage:

• `app/` or `pages/`
• hero section
• animation code
• image imports
• analytics tags

6. Check Cloudflare dashboard:

• DNS status
• SSL mode
• caching rules
• compression settings
• WAF or bot protection conflicts

7. Verify production environment variables and secrets:

• analytics keys
• email provider keys
• form endpoints

8. Test the contact or waitlist form end to end. 9. Open Search Console or analytics if available to see whether real users are hitting slow routes. 10. Capture a baseline before touching code so you can prove improvement.

A simple diagnosis command I often use during triage:

npx lighthouse https://yourdomain.com \
  --preset=mobile \
  --output=json \
  --output-path=./lighthouse-report.json

Root Causes

| Likely cause | What it looks like | How I confirm it | |---|---|---| | Oversized hero image | Slow LCP on mobile | Network tab shows large image file and delayed render | | Too much client-side JS | High TBT or poor INP | Bundle analyzer shows large route chunk or heavy dependencies | | Third-party scripts | Page stalls before interaction | Waterfall shows analytics/chat widgets blocking main thread | | Bad font loading | Text shifts or appears late | CLS spikes and fonts are loaded without preload or fallback | | Weak caching/CDN setup | Repeat visits still feel slow | Response headers lack cache control or Cloudflare bypasses assets | | Broken deployment config | Assets 404 or redirect loops | Hosting logs show missing files or wrong base path |

The API security lens matters here even on a landing page. If your form posts to an API endpoint with no rate limit, no validation, and weak secret handling, a small traffic spike can become spam abuse, inbox flooding, or leaked credentials through logs.

The Fix Plan

1. Cut first-load weight immediately. I would remove anything not needed above the fold: extra animations, unused UI libraries, heavy icon packs, duplicate analytics tags, and background video unless it directly supports conversion.

2. Fix the hero asset first. The hero image should be compressed aggressively and served in modern formats where possible. For a founder landing page, I want the largest visible asset under about 150 KB to 250 KB if quality allows.

3. Move non-essential work off the critical path. Chat widgets, heatmaps, A/B tools, social embeds, and secondary tracking should load after interaction or after idle time.

4. Make fonts cheap. Use one font family if possible. Preload only what is needed for above-the-fold text and make sure fallback fonts do not cause layout shift.

5. Reduce client rendering pressure in Expo / React Native web output. If this is an Expo web build wrapped as a marketing site, I would check whether too many components are being rendered on first paint when simple static markup would do better.

6. Split content by priority. Hero section first. Testimonials second. FAQ third. Everything else lazy-loaded or deferred if it does not affect conversion.

7. Harden caching at the edge. With Cloudflare in front of production assets, I would set proper cache rules for static files so repeat visits are fast and origin load stays low.

8. Verify redirects and canonical paths. Broken redirect chains can add seconds before content appears and also create SEO problems.

9. Lock down form handling with defensive defaults. Validate inputs server-side, rate limit submissions by IP or session where appropriate, store secrets outside the repo, and avoid logging raw user payloads unless needed for support.

10. Measure again after each change instead of stacking blind fixes. I prefer one safe change at a time so we know exactly what improved LCP or caused regressions.

A practical target set for a founder landing page:

• LCP under 2.5 seconds on mobile.
• CLS under 0.1.
• INP under 200 ms.
• Lighthouse performance score above 85 on mobile.
• First meaningful content visible under 1 second on decent 4G conditions.

Regression Tests Before Redeploy

Before shipping any fix live, I would run these checks:

1. Mobile Lighthouse test on production-like build. 2. Desktop Lighthouse test to catch layout issues. 3. Cross-browser smoke test in Chrome Safari Firefox. 4. Real device check on iPhone Safari and Android Chrome. 5. Form submission test with valid input. 6. Form rejection test with empty fields invalid email oversized text. 7. Check that redirects still work from:

• non-www to www or vice versa
• HTTP to HTTPS
• old campaign URLs to current URLs

8. Confirm no console errors on initial load. 9. Confirm images have correct dimensions so they do not jump around during load. 10. Confirm Cloudflare is not caching personalized pages incorrectly.

Acceptance criteria I would use:

• No broken links on homepage navigation.
• No layout shift greater than 0.1 in Lighthouse.
• No critical JS errors in browser console.
• No form spam spike after release.
• No increase in p95 response time from origin endpoints used by forms.
• No missing environment variables in production logs.

Prevention

I would put guardrails in place so this does not come back two weeks later after another "quick edit."

• Add performance budgets for bundle size and image weight.
• Require Lighthouse checks before deploy if possible.
• Keep third-party scripts under review because they are usually where performance debt hides.
• Use code review focused on behavior first: loading order, render blocking risk, data exposure risk, broken redirects.
• Treat form endpoints like API surfaces: validate input server-side, rate limit requests,

sanitize logs, rotate secrets, and keep least privilege access for email and deployment accounts.

• Monitor uptime plus key user actions such as page load success and form completion rate.
• Review Core Web Vitals weekly after launch instead of waiting for complaints.
• Keep one source of truth for DNS,, email auth,, SSL,, and deployment access so founders do not lose control during handoff.

If you want one rule from me: never ship a marketing page that depends on hope instead of measurement.

When to Use Launch Ready

Use Launch Ready when the problem is bigger than "tweak a component" but smaller than a full redesign project.

It fits best if you have:

• A working React Native or Expo landing page that feels slow in production.
• Weak Core Web Vitals hurting ads or organic traffic.
• DNS or Cloudflare setup that was done ad hoc.
• Forms sending leads but with shaky reliability or no monitoring.
• A founder who needs this fixed in 48 hours without turning it into a long agency cycle.

What you should prepare before I start: 1. Domain registrar access. 2D Cloudflare access if already connected. 3D Hosting/deployment access for Expo/web build target. 4D Email provider access if forms send notifications through SMTP or an API service. 5D Repo access with deploy permissions only where needed. 6D Any analytics account used to measure conversions. 7D A short list of pages that matter most: homepage,, waitlist,, pricing,, contact.

If your current issue is slow pages plus shaky infrastructure around them,,, this is exactly the kind of sprint I would run first before spending money on ads again.,,

References

1D https://roadmap.sh/frontend-performance-best-practices 2D https://roadmap.sh/api-security-best-practices 3D https://roadmap.sh/qa 4D https://developer.chrome.com/docs/lighthouse/overview/ 5D https://docs.expo.dev/guides/performance/

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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.*