Transient cache big amount of wc product sizes - wordpress

Question

I got this code in my function.php which shows available sizes on all the products in the category view of woocommerce.
The problem is that it takes a lot of resources and makes the site slow.
My question is, if I should save the data for each product in a transient cache to speed up the site? But it would require a lot of transients, as each product should have a transitent – Is it a good way to do it like I think or is it bad pratice to have so many transients?
My thought was to make each product have a transient key like:
$key = 'my_transient_key' . $product->get_id();
The function code as it is now:
add_action( 'woocommerce_after_shop_loop_item_title', 'display_instock_sizes', 5 );
function display_instock_sizes() {
global $product;
if ( $product->is_type('variable') ) {
$taxonomy = 'stoerrelse'; // The product attribute taxonomy
$sizes_array = []; // Initializing
// Loop through available variation Ids for the variable product
foreach( $product->get_children() as $child_id ) {
$variation = wc_get_product( $child_id ); // Get the WC_Product_Variation object
if( $variation->is_purchasable() && $variation->is_in_stock() ) {
$term_name = $variation->get_attribute( $taxonomy );
$sizes_array[$term_name] = [$term_name => 'instock'];
}else{
$term_name = $variation->get_attribute( $taxonomy );
$sizes_array[$term_name] = [$term_name => 'outofstock'];
}
}
foreach ($sizes_array as $key => $value) {
if (empty($value)) {
unset($sizes_array[$key]);
}
}
if(empty($sizes_array)){
return;
}
ksort($sizes_array);
echo '<div class="attribute-size-wrapper">';
foreach ($sizes_array as $key => $value) {
foreach ($value as $key => $value) {
echo '<span class="attribute-size"><span class="'.$value.'">' . $key . '</span></span>';
}
}
echo '</div>';
}
}