diff --git a/CHANGELOG-WIP.md b/CHANGELOG-WIP.md
index b4d6651fd7..62a4d71c0a 100644
--- a/CHANGELOG-WIP.md
+++ b/CHANGELOG-WIP.md
@@ -4,6 +4,8 @@
 - It’s now possible to specifically make discounts require a coupon code. ([#3132](https://github.com/craftcms/commerce/issues/3132))
 - Country code defaults to the store’s country when creating a new address on the Order Edit page. ([#3306](https://github.com/craftcms/commerce/issues/3306))
 - Product conditions can now have a “Variant Search” rule. ([#3689](https://github.com/craftcms/commerce/issues/3689))
+- Improved the performance of adding items to the cart.
+- Improved the performance of shipping rule matching when an order condition formula is used. ([3653](https://github.com/craftcms/commerce/pull/3653))
 
 ### Administration
 
diff --git a/src/controllers/CartController.php b/src/controllers/CartController.php
index c4ec3d6a69..2c6b805254 100644
--- a/src/controllers/CartController.php
+++ b/src/controllers/CartController.php
@@ -135,7 +135,7 @@ public function actionUpdateCart(): ?Response
 
         // Get the cart from the request or from the session.
         // When we are about to update the cart, we consider it a real cart at this point, and want to actually create it in the DB.
-        $this->_cart = $this->_getCart(true);
+        $this->_cart = $this->_getCart();
 
         // Can clear line items when updating the cart
         $clearLineItems = $this->request->getParam('clearLineItems');
@@ -580,7 +580,7 @@ private function _getCart(bool $forceSave = false): Order
             // Get the cart from the order number
             $cart = Order::find()->number($orderNumber)->isCompleted(false)->one();
 
-            if (!$cart) {
+            if ($cart === null) {
                 throw new NotFoundHttpException('Cart not found');
             }
 
@@ -590,7 +590,13 @@ private function _getCart(bool $forceSave = false): Order
         $requestForceSave = (bool)$this->request->getBodyParam('forceSave');
         $doForceSave = ($requestForceSave || $forceSave);
 
-        return Plugin::getInstance()->getCarts()->getCart($doForceSave);
+        $this->_cart = Plugin::getInstance()->getCarts()->getCart($doForceSave);
+
+        if (!$this->_cart->id) {
+            Craft::$app->getElements()->saveElement($this->_cart, false);
+        }
+
+        return $this->_cart;
     }
 
     /**
@@ -685,7 +691,7 @@ private function _setAddresses(): void
                     $this->_cart->sourceBillingAddressId = $billingAddressId;
 
                     /** @var Address $cartBillingAddress */
-                    $cartBillingAddress = Craft::$app->getElements()->duplicateElement($userBillingAddress,  [
+                    $cartBillingAddress = Craft::$app->getElements()->duplicateElement($userBillingAddress, [
                         'owner' => $this->_cart,
                     ]);
                     $this->_cart->setBillingAddress($cartBillingAddress);
diff --git a/src/models/ShippingRule.php b/src/models/ShippingRule.php
index b6c9388b74..78dc9aa8c6 100644
--- a/src/models/ShippingRule.php
+++ b/src/models/ShippingRule.php
@@ -229,8 +229,9 @@ function($attribute) {
                         if (!$order) {
                             $order = new Order();
                         }
+                        $orderAsArray = Plugin::getInstance()->getShippingMethods()->getSerializedOrderForMatchingRules($order);
                         $orderConditionParams = [
-                            'order' => $order->toArray([], ['lineItems.snapshot', 'shippingAddress', 'billingAddress']),
+                            'order' => $orderAsArray,
                         ];
                         if (!Plugin::getInstance()->getFormulas()->validateConditionSyntax($this->{$attribute}, $orderConditionParams)) {
                             $this->addError($attribute, Craft::t('commerce', 'Invalid order condition syntax.'));
@@ -273,10 +274,9 @@ public function matchOrder(Order $order): bool
         $lineItems = $order->getLineItems();
 
         if ($this->orderConditionFormula) {
-            $fieldsAsArray = $order->getSerializedFieldValues();
-            $orderAsArray = $order->toArray([], ['lineItems.snapshot', 'shippingAddress', 'billingAddress']);
+            $orderAsArray = Plugin::getInstance()->getShippingMethods()->getSerializedOrderForMatchingRules($order);
             $orderConditionParams = [
-                'order' => array_merge($orderAsArray, $fieldsAsArray),
+                'order' => $orderAsArray,
             ];
             if (!Plugin::getInstance()->getFormulas()->evaluateCondition($this->orderConditionFormula, $orderConditionParams, 'Evaluate Shipping Rule Order Condition Formula')) {
                 return false;
diff --git a/src/services/Carts.php b/src/services/Carts.php
index 72af206fac..f67cdcabaa 100644
--- a/src/services/Carts.php
+++ b/src/services/Carts.php
@@ -99,7 +99,7 @@ public function init()
     /**
      * Get the current cart for this session.
      *
-     * @param bool $forceSave Force the cart to save when requesting it.
+     * @param bool $forceSave Force the cart.
      * @throws ElementNotFoundException
      * @throws Exception
      * @throws Throwable
diff --git a/src/services/ShippingMethods.php b/src/services/ShippingMethods.php
index 77d2aa294e..dbb880dad6 100644
--- a/src/services/ShippingMethods.php
+++ b/src/services/ShippingMethods.php
@@ -59,6 +59,11 @@ class ShippingMethods extends Component
      */
     private ?array $_allShippingMethods = null;
 
+    /**
+     * @var array
+     */
+    private array $_serializedOrdersByNumber = [];
+
     /**
      * Returns the Commerce managed shipping methods stored in the database.
      *
@@ -141,9 +146,31 @@ public function getMatchingShippingMethods(Order $order): array
             $shippingMethods[$method->getHandle()] = $method; // Keep the key being the handle of the method for front-end use.
         }
 
+        // Clear the memoized data so next time we watch to match rules, we get fresh data.
+        $this->_serializedOrdersByNumber = [];
+
         return $shippingMethods;
     }
 
+    /**
+     * Creates an order as an array for matching rules.
+     * We do this centrally here so that we can clear the memoized data centrally.
+     *
+     * @param Order $order
+     * @return array
+     */
+    public function getSerializedOrderForMatchingRules(Order $order): array
+    {
+        if (isset($this->_serializedOrdersByNumber[$order->number])) {
+            return $this->_serializedOrdersByNumber[$order->number];
+        }
+
+        $fieldsAsArray = $order->getSerializedFieldValues();
+        $orderAsArray = $order->toArray([], ['lineItems.snapshot', 'shippingAddress', 'billingAddress']);
+        $this->_serializedOrdersByNumber[$order->number] = array_merge($orderAsArray, $fieldsAsArray);
+        return $this->_serializedOrdersByNumber[$order->number];
+    }
+
     /**
      * Get a matching shipping rule for Order and shipping method.
      *