Collections Add to Cart vs Ultimate Sales Boost: Shopify Performance Comparison
Collections Add to Cart wins with Grade C vs Grade D — a one-grade performance difference that compounds on mobile devices.
Both apps provide post-purchase upsell and cross-sell 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 | Collections Add to Cart | Ultimate Sales Boost | Faster |
|---|---|---|---|
| Overall Grade | C | D | Collections Add to Cart |
| JS Payload | 185.75 KB | 645.46 KB | Collections Add to Cart |
| CPU Desktop | 21 ms | 55 ms | Collections Add to Cart |
| CPU Mobile | 74 ms | 318 ms | Collections Add to Cart |
| Layout Shift | 0.0 | 0.0006 | Collections Add to Cart |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Collections Add to Cart — The Faster Option (Grade C)
Collections Add to Cart scores Grade C with a JS payload of 185.75 KB and 21 ms desktop CPU execution. Mobile CPU: 74 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 Collections Add to Cart speed report →
Ultimate Sales Boost — The Heavier Option (Grade D)
Ultimate Sales Boost scores Grade D with a JS payload of 645.46 KB and 55 ms desktop CPU execution. Mobile CPU: 318 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 Ultimate Sales Boost speed report →
When to Choose Collections Add to Cart
- 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 Ultimate Sales Boost
- 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
Winner: Collections Add to Cart — Collections Add to Cart wins with Grade C vs Grade D — a one-grade performance difference that compounds on mobile devices.
Both apps carry Grade C — see StackConflict’s full Upsell 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.