diff --git a/includes/class-wc-cart-session.php b/includes/class-wc-cart-session.php
index 4defeac001b..66a3ed94366 100644
--- a/includes/class-wc-cart-session.php
+++ b/includes/class-wc-cart-session.php
@@ -50,7 +50,12 @@ final class WC_Cart_Session {
 		add_action( 'woocommerce_after_calculate_totals', array( $this, 'set_session' ) );
 		add_action( 'woocommerce_cart_loaded_from_session', array( $this, 'set_session' ) );
 		add_action( 'woocommerce_removed_coupon', array( $this, 'set_session' ) );
-		add_action( 'woocommerce_cart_updated', array( $this, 'persistent_cart_update' ) );
+
+		// Persistent cart stored to usermeta.
+		add_action( 'woocommerce_add_to_cart', array( $this, 'persistent_cart_update' ) );
+		add_action( 'woocommerce_cart_item_removed', array( $this, 'persistent_cart_update' ) );
+		add_action( 'woocommerce_cart_item_restored', array( $this, 'persistent_cart_update' ) );
+		add_action( 'woocommerce_cart_item_set_quantity', array( $this, 'persistent_cart_update' ) );
 
 		// Cookie events - cart cookies need to be set before headers are sent.
 		add_action( 'woocommerce_add_to_cart', array( $this, 'maybe_set_cart_cookies' ) );
@@ -249,7 +254,7 @@ final class WC_Cart_Session {
 	 * Delete the persistent cart permanently.
 	 */
 	public function persistent_cart_destroy() {
-		if ( get_current_user_id() ) {
+		if ( get_current_user_id() && apply_filters( 'woocommerce_persistent_cart_enabled', true ) ) {
 			delete_user_meta( get_current_user_id(), '_woocommerce_persistent_cart_' . get_current_blog_id() );
 		}
 	}
diff --git a/includes/class-wc-cart.php b/includes/class-wc-cart.php
index fd65585b9bd..f06e6f57d25 100644
--- a/includes/class-wc-cart.php
+++ b/includes/class-wc-cart.php
@@ -1163,27 +1163,39 @@ class WC_Cart extends WC_Legacy_Cart {
 	}
 
 	/**
-	 * Set the quantity for an item in the cart.
+	 * Set the quantity for an item in the cart using it's key.
 	 *
 	 * @param string $cart_item_key contains the id of the cart item.
 	 * @param int    $quantity contains the quantity of the item.
-	 * @param bool   $refresh_totals whether or not to calculate totals after setting the new qty.
+	 * @param bool   $refresh_totals whether or not to calculate totals after setting the new qty. Can be used to defer calculations if setting quantities in bulk.
 	 * @return bool
 	 */
 	public function set_quantity( $cart_item_key, $quantity = 1, $refresh_totals = true ) {
 		if ( 0 === $quantity || $quantity < 0 ) {
-			do_action( 'woocommerce_before_cart_item_quantity_zero', $cart_item_key, $this );
-			unset( $this->cart_contents[ $cart_item_key ] );
-		} else {
-			$old_quantity                                      = $this->cart_contents[ $cart_item_key ]['quantity'];
-			$this->cart_contents[ $cart_item_key ]['quantity'] = $quantity;
-			do_action( 'woocommerce_after_cart_item_quantity_update', $cart_item_key, $quantity, $old_quantity, $this );
+			// If we're setting qty to 0 we're removing the item from the cart.
+			return $this->remove_cart_item( $cart_item_key );
 		}
 
+		// Update qty.
+		$old_quantity                                      = $this->cart_contents[ $cart_item_key ]['quantity'];
+		$this->cart_contents[ $cart_item_key ]['quantity'] = $quantity;
+
+		do_action( 'woocommerce_after_cart_item_quantity_update', $cart_item_key, $quantity, $old_quantity, $this );
+
 		if ( $refresh_totals ) {
 			$this->calculate_totals();
 		}
 
+		/**
+		 * Fired after qty has been changed.
+		 *
+		 * @since 3.6.0
+		 * @param string  $cart_item_key contains the id of the cart item. This may be empty if the cart item does not exist any more.
+		 * @param int     $quantity contains the quantity of the item.
+		 * @param WC_Cart $this Cart class.
+		 */
+		do_action( 'woocommerce_cart_item_set_quantity', $cart_item_key, $quantity, $this );
+
 		return true;
 	}