Cart price rules are one of Magento's most powerful marketing features — and one of the fastest ways to tank your store's performance if you're not careful.
In this guide, I'll walk you through why cart price rules slow things down, how to measure the impact, and what you can do about it — from rule design and indexing to caching and database optimization.
Why Cart Price Rules Are Expensive
Every time a customer adds, removes, or updates an item in their cart, Magento re-validates all active cart price rules. Here's what happens under the hood:
All active rules are loaded — Magento fetches every active rule from salesrule and related tables
