Caption vs Poptin: Shopify Performance Comparison
Both apps score Grade D — Caption has the edge with 76 ms vs 675 ms desktop CPU execution.
Both apps provide popup, email capture, and conversion optimization 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 | Caption | Poptin | Faster |
|---|---|---|---|
| Overall Grade | D | D | Tie |
| JS Payload | 517.67 KB | 362.66 KB | Poptin |
| CPU Desktop | 76 ms | 675 ms | Caption |
| CPU Mobile | 127 ms | 941 ms | Caption |
| Layout Shift | 0.0 | 0.0 | Caption |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Caption — The Faster Option (Grade D)
Caption scores Grade D with a JS payload of 517.67 KB and 76 ms desktop CPU execution. Mobile CPU: 127 ms. Even as the faster of the two options, merchants on mobile-heavy stores should weigh its impact on their combined app stack.
View full Caption speed report →
Poptin — The Heavier Option (Grade D)
Poptin scores Grade D with a JS payload of 362.66 KB and 675 ms desktop CPU execution. Mobile CPU: 941 ms. This places it in the heavier half of StackConflict’s benchmark dataset — merchants running mobile-first stores should evaluate whether the feature value justifies the performance tradeoff.
View full Poptin speed report →
When to Choose Caption
- Its unique feature set has no lighter equivalent in StackConflict’s database
- Your store traffic is predominantly desktop
- You have already removed or lightened other heavy scripts to compensate
When to Choose Poptin
- Its unique feature set has no lighter equivalent in StackConflict’s database
- Your store traffic is predominantly desktop
- You have already removed or lightened other heavy scripts to compensate
Performance Verdict
Result: Comparable — Both apps score Grade D — Caption has the edge with 76 ms vs 675 ms desktop CPU execution.
Both apps carry Grade D — see StackConflict’s full Popups rankings for lighter alternatives.
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.