Custom Form Builder by Websyms vs Decify: Shopify Performance Comparison
Decify wins with Grade B vs Grade C — a one-grade performance difference that compounds on mobile devices.
Both apps provide forms, quizzes, and surveys 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 | Custom Form Builder by Websyms | Decify | Faster |
|---|---|---|---|
| Overall Grade | C | B | Decify |
| JS Payload | 325.89 KB | 140.41 KB | Decify |
| CPU Desktop | 69 ms | 11 ms | Decify |
| CPU Mobile | 220 ms | 31 ms | Decify |
| Layout Shift | 0.0 | 0.0 | Custom Form Builder by Websyms |
Mobile CPU measured with 4× CDP throttle (mid-range Android). Tested 2026-05-30.
Decify — The Faster Option (Grade B)
Decify scores Grade B with a JS payload of 140.41 KB and 11 ms desktop CPU execution. Mobile CPU: 31 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 Decify speed report →
Custom Form Builder by Websyms — The Heavier Option (Grade C)
Custom Form Builder by Websyms scores Grade C with a JS payload of 325.89 KB and 69 ms desktop CPU execution. Mobile CPU: 220 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 Custom Form Builder by Websyms speed report →
When to Choose Custom Form Builder by Websyms
- 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 Decify
- 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
Winner: Decify — Decify wins with Grade B vs Grade C — a one-grade performance difference that compounds on mobile devices.
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.