Prestashop product ORDER BY RAND optimization

Heelo StackOverflow community!

At the beginning I want to say hello and that I am not professional programmer - just an amateur who sometimes edit something. That is why I am asking You for help that I think will help a lot of people.

I am using Prestashop Related Product PRO plugin that is really helpful when it comes to show some random products from the same category but it is using default Prestashop order by rand method and when I enable this method to show 24 random products that product page idle loading time is from 4000ms to 7000ms because it is waiting for database to show some random products.

When I reduce it to 8 products it is 1500-2000ms but it is still too long when it comes to SEO score. I was looking for solution in the pluging but I couldn't figure it out but I found this:

Presta 1.6.1.4 here. In classes\Category.php something about line 744 we have something like this:

$sql = 'SELECT p.*, product_shop.*, stock.out_of_stock, IFNULL(stock.quantity, 0) AS quantity'.(Combination::isFeatureActive() ? ', IFNULL(product_attribute_shop.id_product_attribute, 0) AS id_product_attribute,
                product_attribute_shop.minimal_quantity AS product_attribute_minimal_quantity' : '').', pl.`description`, pl.`description_short`, pl.`available_now`,
                pl.`available_later`, pl.`link_rewrite`, pl.`meta_description`, pl.`meta_keywords`, pl.`meta_title`, pl.`name`, image_shop.`id_image` id_image,
                il.`legend` as legend, m.`name` AS manufacturer_name, cl.`name` AS category_default,
                DATEDIFF(product_shop.`date_add`, DATE_SUB("'.date('Y-m-d').' 00:00:00",
                INTERVAL '.(int)$nb_days_new_product.' DAY)) > 0 AS new, product_shop.price AS orderprice
            FROM `'._DB_PREFIX_.'category_product` cp
            LEFT JOIN `'._DB_PREFIX_.'product` p
                ON p.`id_product` = cp.`id_product`
            '.Shop::addSqlAssociation('product', 'p').
            (Combination::isFeatureActive() ? ' LEFT JOIN `'._DB_PREFIX_.'product_attribute_shop` product_attribute_shop
            ON (p.`id_product` = product_attribute_shop.`id_product` AND product_attribute_shop.`default_on` = 1 AND product_attribute_shop.id_shop='.(int)$context->shop->id.')':'').'
            '.Product::sqlStock('p', 0).'
            LEFT JOIN `'._DB_PREFIX_.'category_lang` cl
                ON (product_shop.`id_category_default` = cl.`id_category`
                AND cl.`id_lang` = '.(int)$id_lang.Shop::addSqlRestrictionOnLang('cl').')
            LEFT JOIN `'._DB_PREFIX_.'product_lang` pl
                ON (p.`id_product` = pl.`id_product`
                AND pl.`id_lang` = '.(int)$id_lang.Shop::addSqlRestrictionOnLang('pl').')
            LEFT JOIN `'._DB_PREFIX_.'image_shop` image_shop
                ON (image_shop.`id_product` = p.`id_product` AND image_shop.cover=1 AND image_shop.id_shop='.(int)$context->shop->id.')
            LEFT JOIN `'._DB_PREFIX_.'image_lang` il
                ON (image_shop.`id_image` = il.`id_image`
                AND il.`id_lang` = '.(int)$id_lang.')
            LEFT JOIN `'._DB_PREFIX_.'manufacturer` m
                ON m.`id_manufacturer` = p.`id_manufacturer`
            WHERE product_shop.`id_shop` = '.(int)$context->shop->id.'
                AND cp.`id_category` = '.(int)$this->id
                .($active ? ' AND product_shop.`active` = 1' : '')
                .($front ? ' AND product_shop.`visibility` IN ("both", "catalog")' : '')
                .($id_supplier ? ' AND p.id_supplier = '.(int)$id_supplier : '');

    if ($random === true) {
        $sql .= ' ORDER BY RAND() LIMIT '.(int)$random_number_products;
    } else {
        $sql .= ' ORDER BY '.(!empty($order_by_prefix) ? $order_by_prefix.'.' : '').'`'.bqSQL($order_by).'` '.pSQL($order_way).'
        LIMIT '.(((int)$p - 1) * (int)$n).','.(int)$n;
    }

and if I am not wrong this is responsible for showing off products on categories pages (including some plugins as well). Really bad order by rand(). As You can see there is a line

if ($random === true) {
        $sql .= ' ORDER BY RAND() LIMIT '.(int)$random_number_products;
    }

and IMHO this is the key when we can start some changes. I found an articles about optimizing mysql order by rand query with some really satisfying results. You can read them here

http://ift.tt/1qcJP43

and here

http://ift.tt/NcpQOP (in this case the results were just amazing)

But there is a case. My programming skills are limited to implement those methods into Prestashop :( This is just way complicated for me so can someone help me with editing those lines with one of new methods. Can anyone with better experience and knowledge can help me? Or invent something which is better then those which I proposed? I will be very grateful.