magento2 – Magento 2 default checkout page too slow

3 with default checkout but it loading too slow
in that too

rest/default/V1/guest-carts/W4tUoafhV2AvU8CeJcnlzuALWRqSzfE1/shipping-information and payment-information

these api call taking time i disabled used payment methods and shipping
implemented cdn
Fallowed https://onilab.com/blog/magento-checkout-slow-fix-it-in-8-simple-steps/
https://bsscommerce.com/blog/magento-2-checkout-slow/

can any one tell how we can solve