Very simple change to remove the get variable ?ip=1 from websites that were not running Instantpage.
The ?ip=1 is added to cart and checkout urls to prevent them from being prefetched via instantpage.
If a site owner still wants to prevent this string being added to cart and checkout urls they can use the following filter to remove them
// add to funcitons.php
add_filter('sb_optimizer_woocommerce_instantpage_urls', '__return_false');