Super Long TTFB when no cache

Hi, i'm using openlitespeed with lscache.

Openlitespeed is great when the cache is hit. The TTFB just 600ms-800ms.

But when the cache is miss, the TTFB is very long up to 7s to 13s.
I try to disable the lscache but the problem is still going. The lscache crawler is always missed.

Any solution to fix it? thanks.

LiteSpeed Report
Report number: NLWMMIJZ