Example my forum’s software, Xenforo serves css via css.php file so Cloudflare doesn’t cache it by default as it only caches files with image extensions and .php isn’t a valid static file cache extension. So you can setup a page rule to tell Cloudflare to cache css.php requests
How are you testing TTFB ? You’re testing the wrong metric. CF Argo is about improving one aspect of page speed = server connection response time which makes up a part of overall TTFB but there are other factors that combine to make up TTFB.
Also CF Argo’s benefits will be geographically relative. Your biggest gains are with data center/countries further away from your origin server location. And smallest gains will be with country visitors closest to your origin location.
I posted my CF Argo adventures on my forums including the server response time metrics before and after CF Argo to confirm it working at https://community.centminmod.com/threads/cloudflare-argo-smart-routing-in-action.17517/
Cloudflare Argo has improved my server response time by 61.94% and it shows in my Google Analytics/Datastudio page speed stats in 2nd screenshot. This is current Cloudflare Argo statistics via dashboard and my own custom Argo Analytics API query script for per Cloudflare datacenter metrics
left side Cloudflare Argo stats from dashboard console vs right side my own Argo Analytics API query script to get Argo metrics on a per datacenter basis. As expected, the biggest benefit for Argo will be for visitors further away from your origin server’s geographic location. For me my origin is in US West Coast, so datacenters like SEA (Seattle) and LAX (Los Angles) will have lower % percentage improvement for server response time ~ 41.27% and 41.11% respectively. While datacenters further away like DME (Moscow) and DUB (Dubia) have much higher % percentage improvements for server response time ~ 67.07% and 75.75% respectively.
Digging deeper into my forums Google Analytics via Google Data Studio and filtering pagespeed metrics by sub-continents. This is the pagespeed stats just for European visitors making up Northern, Southern, Eastern and Western Europe for May 5th to May 19th where Cloudflare Argo was enabled on May 14th.
Note up 90-95% of visitors are desktop so the mobile stats some days may have 0 mobile visitors or mobile visitors who use web browsers without reportable metrics.
Again Cloudflare Argo effects your server response times so average server response times are the focus here. As you can see from May 14th onwards, average server response times have fallen for Cloudflare Argo smart routed traffic which from above Argo metrics is around 87% of the requests so still 13% of requests didn’t go through Cloudflare Argo.
Desktop visitors for Europe page speed
Yes I am using both for my forums