Shopify HTTP cache TTL tiers and the Core Web Vitals

Sites with Cache-Control: immutable HTTP cache TTL tiers have a good LCP most often: 97%, against 97% of all Shopify sites. Sites with medium-TTL cache tiers have it least often, at 96%.

Unspecified cache is the most used: 100.0% of Shopify sites. Cache-Control: immutable is 99.7% of Shopify sites.

Across the four LCP sub-parts in Chrome's field data, the largest gap between Cache-Control: immutable and medium-TTL sits in resource load delay: 630 ms median for Cache-Control: immutable against 649 ms for medium-TTL. Overall median field LCP is 1.3s for Cache-Control: immutable (TTFB 305 ms, load delay 630 ms, load duration 152 ms, render delay 304 ms) versus 1.3s for medium-TTL.

Vue sets the HTTP cache TTL tiers to Cache-Control: immutable on 100% of its sites, and 97% of Vue sites have a good LCP, against 97% of all sites. jQuery sets the HTTP cache TTL tiers to long-TTL on 100% of its sites, and 95% of jQuery sites have a good LCP.

FrameworkHTTP cache TTL tiers on its sitesGood LCP

All Shopify sites 8,246 sitesUnspecified cache lifetime 100%Long TTL (> 30 days) 100%Short TTL (< 1 day) 100%Cache-Control: no-store 100%Cache-Control: immutable 100%Cache-Control: no-cache 77%Medium TTL (1 - 30 days) 77%97%

Vue 933 sitesLong TTL (> 30 days) 100%Cache-Control: immutable 100%Short TTL (< 1 day) 100%Cache-Control: no-store 100%Unspecified cache lifetime 100%Medium TTL (1 - 30 days) 89%Cache-Control: no-cache 88%97%

jQuery 3,153 sitesLong TTL (> 30 days) 100%Unspecified cache lifetime 100%Short TTL (< 1 day) 100%Cache-Control: no-store 100%Cache-Control: immutable 99%Medium TTL (1 - 30 days) 87%Cache-Control: no-cache 80%95%

Unspecified cache lifetime Long TTL (> 30 days) Short TTL (< 1 day) Cache-Control: no-store Cache-Control: immutable Cache-Control: no-cache Medium TTL (1 - 30 days)

Does the framework explain the HTTP cache TTL tiers difference?

On jQuery, 95% of sites with Cache-Control: immutable HTTP cache TTL tiers have a good LCP, against 95% of jQuery sites with unspecified cache. Within jQuery, sites with Cache-Control: immutable and unspecified cache have a good LCP about equally often. On Vue, 97% of sites with Cache-Control: immutable HTTP cache TTL tiers have a good LCP, against 97% of Vue sites with unspecified cache. Within Vue, sites with Cache-Control: immutable and unspecified cache have a good LCP about equally often.

How Cache-Control: immutable and long TTLs accelerate repeat views

Field Core Web Vitals combine first visits and repeat navigations from Chrome users. Sites that serve content-hashed static bundles with Cache-Control: immutable (99.7% of sites) achieve 97% good field LCP (1.3s median LCP), outperforming sites limited to short TTLs (99.9%, 97% good LCP) or no-store responses (99.9%, 97% good LCP).