improve page speed

Hello my friends,

I have noticed that my page is sometimes really slow. I started a GTmetrix check, and it showed me that even an empty page takes several seconds, a standard page has an initial server response of 3-5 seconds, the worst page I found had 11 seconds for initial, and a total of 15 seconds to be loaded. My webprovider told me that it's not a technical problem, I should check my settings and macros. But honestly, I think I'm not overly using them, and I have no idea how to improve this.

So, is there anyone around here who has experience in improving foswiki speed, or tips on where to search or what to change?
If you're interested, here the site: http://klingon.wiki/En/MainPage

If it's a thing that can be easily done, I'd be willing to compensate the time.

-- Lieven - 23 Nov 2021

Your base line is okay. Not rapid but acceptable looking at

http://klingon.wiki/En/MainPage?section=foo;skin=text (no text no skin): 550ms
http://klingon.wiki/En/MainPage?section=foo (no text): 2.5s
http://klingon.wiki/En/MainPage: 4-5s (varying a lot)

What to try next:

if there are lots of webs:
- remove any %WEBLIST or the like from the skin
- try replacing %WEBLIST with %FLEXWEBLIST from FlexWebListPlugin as it caches web information
try disable %SEARCH one by one watching the numbers
try adding a TLS certificate, this will bring you the more modern HTTP/2 protocol
try PageCaching for SEARCH heavy pages
try XSendFileContrib replacing viewfile if not already in place
set $Foswiki::cfg{FastCGIContrib}{MaxRequests} 0= and increase $Foswiki::cfg{FastCGIContrib}{MaxSize} presumably to 1G; this will let the foswiki backends build up more memory caches being reused on consecutive calls
replace all %SEARCH with %DBQUERY
replace all %INCLUDE with %DBCALL