If your pages load slowly, you can check whether the cause is caching or origin render time by comparing two loads of the same page.
- Load the page normally. This is the cached load.
- Load the page again with a random query string added to the URL. This is the cache-busted load.
- Compare the two load times.
If the cached load is fast and the cache-busted load is much slower, the bottleneck is origin render time. This means you need to optimize the uncached page building process rather than fix caching.