# Scalability

> How AndOr stays fast in checkout and on your storefront as your store grows, and the limits Shopify sets.

Source: https://backtrackhq.com/docs/enterprise/scalability/

AndOr is built so that a busy day on your store is a normal day for the
app.

## Checkout runs on Shopify

Discounts and checkout rules run inside Shopify checkout, through
Shopify Functions. They grow with Shopify's checkout, and checkout never
waits for AndOr.

## The storefront stays light

- Widgets read their data in your theme, on the server. A page view
  does not call AndOr to find a discount.
- Scripts load only on pages that need them, and never block the page
  from drawing.
- Widgets keep their space while they load, so the page does not jump.

See [Performance](https://backtrackhq.com/docs/developers/performance/).

## Busy periods

In a very busy period, some numbers in Analytics are estimated from a
sample. Offers and widgets keep showing to every shopper. See
[How we count](https://backtrackhq.com/docs/analytics/how-we-count/#busy-periods).

## Limits set by Shopify

- Shopify allows at most 25 active functions of each type on a store,
  shared with every app.
- Each rule has up to 10 KB of settings at checkout.

See [Limits](https://backtrackhq.com/docs/rules/limits/).

## Plans for bigger stores

Plans differ by your store's orders a month, the number of active
rules and rule blocks, and the rule tools. The biggest plan, Scale,
covers up to 2,000 orders a month, 25 active rules per rule type,
Shopify's maximum, and 15 rule blocks per rule. More than 2,000 orders a month?
[Contact us](mailto:andor@backtrackhq.com) for an Enterprise plan. See
[Plans and billing](https://backtrackhq.com/docs/get-started/plans-and-billing/).