Flashy vs Klaviyo: Shopify Performance Comparison
⏳ Data pending for Klaviyo — our scanner captured only the async loader stub for this app. Full bundle metrics are being collected from live Shopify storefronts. Once available, this page will show a complete head-to-head comparison.
Both Flashy and Klaviyo provide email marketing and automation functionality for Shopify stores.
What We Know: Flashy (Benchmarked)
Flashy has been measured in StackConflict’s clean-room lab:
| Metric | Flashy |
|---|---|
| Overall Grade | B |
| JS Payload | 42.34 KB |
| CPU Desktop | 21 ms |
| CPU Mobile | 83 ms (0.1s) |
| Layout Shift | 0.0006 |
Grade B means Flashy passes every StackConflict threshold — safe to install on any storefront including mobile-first stores.
View full Flashy speed report →
Pending: Klaviyo
StackConflict’s scanner detected that Klaviyo uses an async JavaScript loader — a small stub that only initialises its full bundle on a real, authenticated Shopify storefront. This means our lab environment captured the tiny stub file only, not the production bundle that actually runs on live stores.
We are collecting real bundle data by scanning public Shopify storefronts. Once captured, the head-to-head metrics for Klaviyo will appear here automatically.
View Klaviyo on Shopify App Store →
About This Test
StackConflict measures each Shopify app in an isolated clean-room environment — a Playwright-controlled browser with no other scripts installed. V8 CPU cost is the ScriptDuration delta measured before and after bundle injection. Mobile CPU applies the standard 4× Lighthouse slowdown factor.
Flashy data from the StackConflict Lab (2026-05-30). Klaviyo data pending.