Monocle vs Zephyr Shopify DataLayer: Shopify Performance Comparison
Both apps score Grade B — Zephyr Shopify DataLayer has the edge with 18 ms vs 24 ms desktop CPU execution.
Both apps provide heatmaps, session recording, and analytics 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 | Monocle | Zephyr Shopify DataLayer | Faster |
|---|---|---|---|
| Overall Grade | B | B | Tie |
| JS Payload | 109.77 KB | 64.5 KB | Zephyr Shopify DataLayer |
| CPU Desktop | 24 ms | 18 ms | Zephyr Shopify DataLayer |
| CPU Mobile | 54 ms | 49 ms | Zephyr Shopify DataLayer |
| Layout Shift | 0.0 | 0.0006 | Monocle |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Zephyr Shopify DataLayer — The Faster Option (Grade B)
Zephyr Shopify DataLayer scores Grade B with a JS payload of 64.5 KB and 18 ms desktop CPU execution. Mobile CPU: 49 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 Zephyr Shopify DataLayer speed report →
Monocle — The Heavier Option (Grade B)
Monocle scores Grade B with a JS payload of 109.77 KB and 24 ms desktop CPU execution. Mobile CPU: 54 ms. Performance is acceptable but worth monitoring, particularly on stores with high mobile traffic share.
View full Monocle speed report →
When to Choose Monocle
- 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 Zephyr Shopify DataLayer
- 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 — Zephyr Shopify DataLayer has the edge with 18 ms vs 24 ms desktop CPU execution.
Install Zephyr Shopify DataLayer →
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.