non-cached woocommerce pages = TTFB 8 to 13 seconds

Hi, I have a shop that has litespeed cache plugin installed, which is lighting fast on pages that are cached.

However, this is a very busy site, also with an API to an epos that updates stock levels.. This results in the cache for the products to be purged.

On purged pages, the TTFB can be anywhere from 8 seconds to 13 seconds. Until the page is cached again, then the TTFB is 20ms and total page load speed = 500ms.

My hosts have been amazing in attempting to fix this problem , but so far they have been unsuccessful.

In addition, the setting we have = Purge product only when the stock status changes. Do not purge categories on changes to the quantity or stock status. Yet, the product category pages are also being purged.

With Litespeed disabled, the average TTFB is 300ms, and total page load = 2 to 4 seconds.

Can anyone help with this? Or point me in the right direction on how to fix this?

I have tested with WP Optimize Cache, and while their cached pages are not as quick as litespeed, the non-cached pages TTFB = 300ms.

I can’t workout why the TTFB is so bad with Litespeed? Considering products stock levels change every few minutes, the lag is causing a loss of sales.

Any advice is appreciated.