Try playing with Ajax in WBW Product Filter. Namely, with the Force theme themes option, and product block selectors.
Its activation/deactivation affects performance in some setups, since the operating principle of Ajax changes and this can also affect the speed of processing products.
Hye, I attached the files screenshot that takes time almost 6s below. I have one question why two ajax called again and again with same carry data. https://ibb.co/6JzzRc9