Monocle vs Zephyr DataLayer: Shopify Performance Comparison
Both apps score Grade B — Zephyr DataLayer has the edge with 16 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 DataLayer | Faster |
|---|---|---|---|
| Overall Grade | B | B | Tie |
| JS Payload | 109.77 KB | 106.96 KB | Zephyr DataLayer |
| CPU Desktop | 24 ms | 16 ms | Zephyr DataLayer |
| CPU Mobile | 54 ms | 54 ms | Monocle |
| Layout Shift | 0.0 | 0.0 | Monocle |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Zephyr DataLayer — The Faster Option (Grade B)
Zephyr DataLayer scores Grade B with a JS payload of 106.96 KB and 16 ms desktop CPU execution. Mobile CPU: 54 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 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 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 DataLayer has the edge with 16 ms vs 24 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.