LoyaltyLion vs Smile.io: Shopify Performance Comparison
Both apps score Grade B — Smile.io has the edge with 3 ms vs 18 ms desktop CPU execution.
Both apps provide loyalty rewards and referral program functionality for Shopify stores. This page presents StackConflict’s independent lab results for both — measured in a clean-room environment with no other apps installed.
Head-to-Head Metrics
| Metric | LoyaltyLion | Smile.io | Faster |
|---|---|---|---|
| Overall Grade | B | B | Tie |
| JS Payload | 113.45 KB | 104.75 KB | Smile.io |
| CPU Desktop | 18 ms | 3 ms | Smile.io |
| CPU Mobile | 130 ms | 5 ms | Smile.io |
| Layout Shift | 0.0 | 0.0 | LoyaltyLion |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Smile.io — The Faster Option (Grade B)
Smile.io scores Grade B with a JS payload of 104.75 KB and 3 ms desktop CPU execution. Mobile CPU: 5 ms. It passes every StackConflict threshold for payload, CPU, and layout stability — making it safe to install on any storefront including mobile-first stores where Time-to-Interactive directly impacts conversion.
View full Smile.io speed report →
LoyaltyLion — The Heavier Option (Grade B)
LoyaltyLion scores Grade B with a JS payload of 113.45 KB and 18 ms desktop CPU execution. Mobile CPU: 130 ms. Performance is acceptable but worth monitoring, particularly on stores with high mobile traffic share.
View full LoyaltyLion speed report →
When to Choose LoyaltyLion
- You need its specific features and can monitor its mobile impact
- Your other apps are lightweight (Grade A) so there is headroom
- You are on desktop-skewed traffic where CPU cost matters less
When to Choose Smile.io
- You need its specific features and can monitor its mobile impact
- Your other apps are lightweight (Grade A) so there is headroom
- You are on desktop-skewed traffic where CPU cost matters less
Performance Verdict
Result: Comparable — Both apps score Grade B — Smile.io has the edge with 3 ms vs 18 ms desktop CPU execution.
About This Test
StackConflict measures each Shopify app in an isolated clean-room environment — a single development store, no other scripts, Playwright-controlled browser. V8 CPU cost is the ScriptDuration delta before and after injection. CLS is captured from the same browser session. Results represent the median of three independent runs with outliers removed.
Data from the StackConflict Lab. Last updated 2026-05-30.