Removing a Woocommerce function update-safe

We have a nasty problem with excessive page load times on Woocommerce product pages. We found out that this is caused by the wc_customer_bought_product() function in /includes/wc-user-functions.php. After removing this function (actually: emptying it), everything is back to normal. Since this function is not hooked, we don't know how to remove it without changing the core file. So, we need somebody, who can write us a snippet for the child theme functions.php