Zend certified PHP/Magento developer

site is super slow GET customer/section/load/?sections=cart&force_new_section_timestamp=false&_=xxxxxx

My site became super slow since yesterday. I can not find out which extension causes this. I thought it might because of the weltpixel Google Tag Manager, i disabled it. run setup:upgrade; setup di:compile; s:s:d, but the site is still very slow.

this is the request that makes the site so slow

https://www.example.com/customer/section/load/?sections=cart&force_new_section_timestamp=false&_=xxxxxxxx

enter image description here

response
{“cart”:{“summary_count”:0,”subtotalAmount”:null,”subtotal”:”$0.00″,”possible_onepage_checkout”:true,”items”:[],”extra_actions”:”

Are you an Amazon customer? Pay now with address and payment details stored in your Amazon account.”,”isGuestCheckoutAllowed”:true,”website_id”:”1″,”storeId”:”1″,”amazon_quote_has_excluded_item”:false,”subtotal_incl_tax”:”$0.00″,”subtotal_excl_tax”:”$0.00″,”data_id”:1571424976}}