diff --git a/services/nginx/app/objects/orders_o.php b/services/nginx/app/objects/orders_o.php
index 1122ce4c..7bcb167a 100644
--- a/services/nginx/app/objects/orders_o.php
+++ b/services/nginx/app/objects/orders_o.php
@@ -1332,31 +1332,42 @@ class orders_o extends db
     {
         // Get the original net amount for the order items, ignoring any temporary net amount set
         self::requireSelected();
-        $order_items = $this->getOrderItems((int)$this->id);
-        //echo 'Calculating net amount for order ID ' . $this->id . ' with ' . count($order_items) . " items\n";
-        return array_sum(array_map(/**
-         * @throws Exception
-         */ function ($item) {
-            if ( (int)$item['price'] > 0 && (int)$item['quantity'] > 0) {
-                return (int)$item['price'] * (int)$item['quantity'];
+        $order_items = (new order_items_o())->getFieldsWhere(
+            ['order_id' => (int)$this->id],
+            ['price', 'quantity', 'product_id']
+        );
+        if (empty($order_items)) {
+            return 0;
+        }
+
+        $total = 0;
+        $department_id = (int)$this->department_id->value();
+        $tmp_user = null;
+        $department_price_cache = [];
+
+        foreach ( $order_items as $item ) {
+            $price = (int)$item['price'];
+            $quantity = (int)$item['quantity'];
+
+            if ($price > 0 && $quantity > 0) {
+                $total += $price * $quantity;
+                continue;
             }
-            // Otherwise we need to get the product price
-            $product = (new products_o())->select((int)$item['product_id']);
-            // Apply the customer discount if applicable
-            $department_price_original = (int)$product->getDepartmentPrice((int)$this->department_id->value());
-            // Get the customers user object
-            $tmp_user = (new users_o())->getUserByCustomerNumber((int)$this->customer_id->value());
-            // Get the discount percentage for the customer
-            $discount = $tmp_user->getCustomPrice((int)$product->id, false);
-            // Calculate the final price after discount
-            $post_discount = (int)round($department_price_original * (1 - ($discount / 100))) * (int)$item['quantity'];
-            //echo 'Adding ' . $post_discount . ' for product ' . $product->name . ' (Original price: ' . $department_price_original . ', Discount: ' . $discount . '%, Quantity: ' . (int)$item['quantity'] . ")\n";
-            $actual_price = (int)$item['price'];
-            if ($actual_price !== $post_discount) {
-                //echo "Warning: The actual price ($actual_price) does not match the calculated price ($post_discount) for product " . $product->name . "\n";
+
+            $product_id = (int)$item['product_id'];
+            if (!isset($department_price_cache[$product_id])) {
+                $product = (new products_o())->select($product_id);
+                $department_price_cache[$product_id] = (int)$product->getDepartmentPrice($department_id);
             }
-            return $post_discount;
-        }, $order_items));
+            if ($tmp_user === null) {
+                $tmp_user = (new users_o())->getUserByCustomerNumber((int)$this->customer_id->value());
+            }
+            $discount = $tmp_user->getCustomPrice($product_id, false);
+            $post_discount = (int)round($department_price_cache[$product_id] * (1 - ($discount / 100))) * $quantity;
+            $total += $post_discount;
+        }
+
+        return $total;
     }
 
     /**
@@ -1624,4 +1635,4 @@ class orders_o extends db
         }
         return $orders;
     }
-}
\ No newline at end of file
+}
diff --git a/services/nginx/app/routes/InvoicingPeriodRoute.php b/services/nginx/app/routes/InvoicingPeriodRoute.php
index 082bcff5..98b9caaa 100644
--- a/services/nginx/app/routes/InvoicingPeriodRoute.php
+++ b/services/nginx/app/routes/InvoicingPeriodRoute.php
@@ -54,6 +54,25 @@ class InvoicingPeriodRoute
         return self::$departmentExcludedFromInvoicingCache[$departmentId];
     }
 
+    /**
+     * Slack summaries are expensive on request latency, so they are opt-in.
+     * Enable with query param `sendSlackSummary=1` or env `INVOICING_PERIOD_SEND_SLACK_SUMMARY=true`.
+     */
+    private static function shouldSendSlackSummary(): bool
+    {
+        $requestOverride = $_GET['sendSlackSummary'] ?? null;
+        if ($requestOverride !== null) {
+            return in_array(strtolower((string)$requestOverride), ['1', 'true', 'yes'], true);
+        }
+
+        $envFlag = getenv('INVOICING_PERIOD_SEND_SLACK_SUMMARY');
+        if ($envFlag === false) {
+            return false;
+        }
+
+        return in_array(strtolower((string)$envFlag), ['1', 'true', 'yes'], true);
+    }
+
 
     /**
      * @param array $collective_results
@@ -538,17 +557,19 @@ class InvoicingPeriodRoute
         $collective_results['subscription_price_department_distribution_parsed'] = $parsed_distribution;
         // Include the collective results in the response
         $response->add_include('collective_subscription_results', $collective_results);
-        // Send summary to slack
-        $slack_message = "Subscription Price Distribution Summary:\n";
-        $slack_message .= "Total Subscription Price: " . $collective_results['total_subscription_price'] . "\n";
-        $slack_message .= "Department Distribution:\n";
-        $tmp_total = 0;
-        foreach ( $collective_results['subscription_price_department_distribution_parsed'] as $department_name => $price ) {
-            $slack_message .= "- " . $department_name . ": " . $price . "\n";
-            $tmp_total += $price;
+        if (self::shouldSendSlackSummary()) {
+            // Send summary to slack
+            $slack_message = "Subscription Price Distribution Summary:\n";
+            $slack_message .= "Total Subscription Price: " . $collective_results['total_subscription_price'] . "\n";
+            $slack_message .= "Department Distribution:\n";
+            $tmp_total = 0;
+            foreach ( $collective_results['subscription_price_department_distribution_parsed'] as $department_name => $price ) {
+                $slack_message .= "- " . $department_name . ": " . $price . "\n";
+                $tmp_total += $price;
+            }
+            $slack_message .= "Total Distribution: " . $tmp_total . "\n";
+            (new slack())->send_message($slack_message, 'Subscription Price Distribution Summary');
         }
-        $slack_message .= "Total Distribution: " . $tmp_total . "\n";
-        (new slack())->send_message($slack_message, 'Subscription Price Distribution Summary');
         return $customersWithSubscriptions;
     }
 
@@ -740,11 +761,13 @@ class InvoicingPeriodRoute
     private static function getOriginalPrice(array $fixed_pricing): array
     {
         global $response;
-        $orders = new orders_o();
+        $order_items = new order_items_o();
         foreach ( $fixed_pricing as &$customer ) {
             if (isset($customer['meta']['fixed_pricing'])) {
                 $original_price = 0;
                 $department_totals = []; // Array to hold totals per department
+
+                $eligible_transaction_department_ids = [];
                 foreach ( $customer['transactions'] as $transaction ) {
                     $department_id = (int)($transaction['department_id'] ?? 0);
                     $excluded = (bool)($transaction['excluded'] ?? false);
@@ -753,16 +776,60 @@ class InvoicingPeriodRoute
                     if ($excluded || $department_id === 10) {
                         continue;
                     }
-
-                    $transaction_original_price = $orders->select((int)$transaction['id'])->getNetAmountForOrderItemsOriginal();
-                    $original_price += $transaction_original_price;
-                    // Initialize the department total if it doesn't exist
-                    if (!isset($department_totals[$department_id])) {
-                        $department_totals[$department_id] = 0;
-                    }
-                    // Add the transaction amount to the department total
-                    $department_totals[$department_id] += $transaction_original_price;
+                    $eligible_transaction_department_ids[(int)$transaction['id']] = $department_id;
                 }
+
+                if (!empty($eligible_transaction_department_ids)) {
+                    $transaction_original_prices = [];
+                    $product_cache = [];
+                    $department_price_cache = [];
+                    $discount_cache = [];
+                    $user = (new users_o())->getUserByCustomerNumber((int)$customer['customer_number']);
+                    $rows = $order_items->getFieldsWhere(
+                        ['order_id' => array_keys($eligible_transaction_department_ids)],
+                        ['order_id', 'product_id', 'price', 'quantity']
+                    );
+
+                    foreach ( $rows as $row ) {
+                        $order_id = (int)$row['order_id'];
+                        $department_id = (int)($eligible_transaction_department_ids[$order_id] ?? 0);
+                        if ($department_id <= 0) {
+                            continue;
+                        }
+                        $product_id = (int)$row['product_id'];
+                        $price = (int)$row['price'];
+                        $quantity = (int)$row['quantity'];
+
+                        if ($price > 0 && $quantity > 0) {
+                            $transaction_original_prices[$order_id] = (int)(($transaction_original_prices[$order_id] ?? 0) + ($price * $quantity));
+                            continue;
+                        }
+
+                        if (!isset($product_cache[$product_id])) {
+                            $product_cache[$product_id] = (new products_o())->select($product_id);
+                        }
+                        if (!isset($department_price_cache[$department_id][$product_id])) {
+                            $department_price_cache[$department_id][$product_id] = (int)$product_cache[$product_id]->getDepartmentPrice($department_id);
+                        }
+                        if (!array_key_exists($product_id, $discount_cache)) {
+                            $discount_cache[$product_id] = $user->getCustomPrice($product_id, false);
+                        }
+                        $post_discount = (int)round($department_price_cache[$department_id][$product_id] * (1 - ($discount_cache[$product_id] / 100))) * $quantity;
+                        $transaction_original_prices[$order_id] = (int)(($transaction_original_prices[$order_id] ?? 0) + $post_discount);
+                    }
+
+                    foreach ( $eligible_transaction_department_ids as $transaction_id => $department_id ) {
+                        $transaction_original_price = (int)($transaction_original_prices[$transaction_id] ?? 0);
+                        $original_price += $transaction_original_price;
+                        // Initialize the department total if it doesn't exist
+                        if (!isset($department_totals[$department_id])) {
+                            $department_totals[$department_id] = 0;
+                        }
+                        // Add the transaction amount to the department total
+                        $department_totals[$department_id] += $transaction_original_price;
+                    }
+                }
+
                 $customer['meta']['fixed_pricing']['original_price'] = $original_price;
                 $customer['meta']['fixed_pricing']['department_totals'] = $department_totals;
                 // Take the relative price of the department totals in relation to the fixed price
@@ -810,25 +877,27 @@ class InvoicingPeriodRoute
         $collective_results = self::parseTheDepartmentIdsToDepartmentNames($collective_results);
         // Include the collective results in the response
         $response->add_include('collective_fixed_pricing_results', $collective_results);
-        // Send slack message with the collective results
-        $slack_message = "Fixed Pricing Invoicing Period Summary:\n";
-        $slack_message .= "Total Fixed Price: " . number_format($collective_results['total_fixed_price'], 2) . " DKK\n";
-        $slack_message .= "Total Original Price: " . number_format($collective_results['total_original_price'], 2) . " DKK\n";
-        $slack_message .= "Department Totals:\n";
-        $tmp_sum = 0;
-        foreach ( $collective_results['total_department_totals_parsed'] as $department_name => $amount ) {
-            $slack_message .= "- " . $department_name . ": " . number_format($amount, 2) . " DKK\n";
-            $tmp_sum += $amount;
+        if (self::shouldSendSlackSummary()) {
+            // Send slack message with the collective results
+            $slack_message = "Fixed Pricing Invoicing Period Summary:\n";
+            $slack_message .= "Total Fixed Price: " . number_format($collective_results['total_fixed_price'], 2) . " DKK\n";
+            $slack_message .= "Total Original Price: " . number_format($collective_results['total_original_price'], 2) . " DKK\n";
+            $slack_message .= "Department Totals:\n";
+            $tmp_sum = 0;
+            foreach ( $collective_results['total_department_totals_parsed'] as $department_name => $amount ) {
+                $slack_message .= "- " . $department_name . ": " . number_format($amount, 2) . " DKK\n";
+                $tmp_sum += $amount;
+            }
+            $slack_message .= "Total Department Totals: " . number_format($tmp_sum, 2) . " DKK\n";
+            $slack_message .= "Relative Department Totals:\n";
+            $tmp_sum = 0;
+            foreach ( $collective_results['total_department_totals_relative_parsed'] as $department_name => $amount ) {
+                $slack_message .= "- " . $department_name . ": " . number_format($amount, 2) . " DKK\n";
+                $tmp_sum += $amount;
+            }
+            $slack_message .= "Total Relative Department Totals: " . number_format($tmp_sum, 2) . " DKK\n";
+            (new slack())->send_message($slack_message, 'Fixed Pricing Invoicing Period Summary');
         }
-        $slack_message .= "Total Department Totals: " . number_format($tmp_sum, 2) . " DKK\n";
-        $slack_message .= "Relative Department Totals:\n";
-        $tmp_sum = 0;
-        foreach ( $collective_results['total_department_totals_relative_parsed'] as $department_name => $amount ) {
-            $slack_message .= "- " . $department_name . ": " . number_format($amount, 2) . " DKK\n";
-            $tmp_sum += $amount;
-        }
-        $slack_message .= "Total Relative Department Totals: " . number_format($tmp_sum, 2) . " DKK\n";
-        (new slack())->send_message($slack_message, 'Fixed Pricing Invoicing Period Summary');
         return $fixed_pricing;
     }