How does the Simple Bundles app affect my Shopify store and theme?

Shopify store page speed or performance 

Simple Bundles works by performing workflow actions solely on the backend using Shopify's Admin API. Since Simple Bundles does not depend on the Shopify theme, no custom code or JavaScript is injected onto the pages and themes. Hence, the Simple Bundles app has no impact on your Shopify store page speed or performance.

Checkout errors 

If you experience errors when trying to check out a new product, these are almost never related to the Simple Bundles app as the app does not inject any code on the cart or checkout pages. If you do run into specific error inventory or shipping errors during checkout, make sure the product variant weight is set up correctly based on your current shipping integration, the product variant is stocked in the correct location(s) and the correct product theme template is being used. Make sure to audit your other apps that modify the theme, especially on cart and checkout to ensure these apps aren't interfering and causing the checkout errors on your store.

Steps before uninstalling the app

Since Simple Bundles does not install any custom code on your storefront, you do not need to perform any code clean-up upon uninstalling the app. When the app is successfully uninstalled, all Shopify API permissions are revoked and the app will not be able to perform any further changes to Shopify orders.