I tried private browsing on Pale Moon - but the search autofill seems linked (so I'm unsure of what I'm doing).
The search box comes up within a second or two, while the search results are almost immediate.
Have you compared the Sysnative mirror to the Carrona mirror?
Using Carrona.org directly, the DRT loads in ~2 seconds. Search results in well under 0.5 sec.
I rarely use private browsing in Pale Moon, my browser uptimes are often in the 6-16 day ballpark unless it's during a beta testing period. I feel private browsing is better suited to short sessions. Search autofill - in the URL (aka Awesome or Location) bar or the separate Search box? If the Location bar, options are found under (Alt) Tools > Options > Privacy > History and Location bar tabs.