Trouble with LCP Score in Shopify Public App

Shopify Apps

Topic summary

A developer is experiencing persistent LCP (Largest Contentful Paint) performance issues with their Shopify public app, despite a fast 200ms server response time. The LCP score consistently remains above 3-4 seconds and fluctuates unpredictably even with minimal changes.

Key metrics:

  • Server response: 200ms
  • LCP score: 3-4+ seconds (consistently high)
  • Behavior: Frequent fluctuations

Suggested solution:
One community member recommends implementing Cloudflare for caching and using its RUM (Real User Monitoring) to identify regional traffic patterns and corresponding LCP metrics. They note that high TTFB (Time To First Byte) is typically the primary cause of elevated LCP scores.

The discussion remains open, with the developer seeking additional optimization strategies and troubleshooting steps to resolve the performance gap between server response time and actual LCP measurements.

Summarized with AI on October 25. AI used: claude-sonnet-4-5-20250929.
1

Hello Shopify Community,

I’m currently facing an issue with the LCP (Largest Contentful Paint) score for my Shopify app. Despite our server responding in about 200ms and ensuring that the app is set up correctly, the LCP score remains consistently above 3-4 seconds. This happens regardless of the changes I make.

Here are some details:

  • Server Response Time: 200ms
  • LCP Score: consistently above 3-4 seconds
  • Observations: The score fluctuates frequently even with minimal changes made.

I would appreciate any insights, suggestions, or troubleshooting steps you could recommend to help improve the LCP score. Are there specific optimizations I should consider or common pitfalls that could lead to this issue?

Thank you for your assistance!

Best,
Er Sanjay

2

Try Cloudflare for Caching and use its RUM for identifying the regional traffic and corresponding LCP. Most of the time, high TTFB is the main cause for LCP hikes.