By default, our Ultimate Upsell app doesn't insert any script inside your theme files. Most of the other apps do that, and then your theme gets messy and it's either impossible to switch theme, or it's a real mess that eventually breaks your store.
That being said, our Ultimate Upsell loads the upsell(s) in your store via an alternative way. That makes it load last. For stores with many apps and many scripts running, it might result in a slow loading speed for your upsells.
We now provide a way to increase loading speed by 4-5x.
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Tabarnapp's mission is to help you get the most of each visit on your Shopify store.