A single PC is experiencing extremely poor performance from Cloud Flare

I have a unusual problem which I have been unable to resolve and could use any assistance someone might provide. A single PC (mine) is having unbelievably slow performance for websites using Cloudflare’s service (which is all of those my company maintains). This is unlikely to be a configuration issue for those sites, as I get the same poor performance from https://www.cloudflare.com/ itself. For context, a lighthouse audit (chrome devtools) put First Contentful Paint at 48.1 seconds for Cloudflare’s home page. Looking at the network waterfall, an excessive amount of time is spent waiting for TTFB, but the content downloads are occasionally not commensurate with their relative payloads either (I see one 41kb js file that took 10s for content download).

This problem does not exist for any other device connected to the same network. The PC in question is a Windows 10 machine and does not experience similar problems with any other website or service that I am aware of. I have tried flushing and re-registering the DNS, Specifying in the network adapter settings to use cloudflare’s own DNS (both IPv4 and IPv6) and clearing Chrome’s DNS cache (though this problem exists with all browsers). No joy.

This is actually not a new problem for me, I’ve been just “dealing with it” for several months, so rest assured the PC has been restarted. Anyone out there have a clue as to what stone I should turn over?

I presume you get an equally slow performance on sitemeer.com as well as with the forum here, right?

Furthermore, I presume you are saying any site not on Cloudflare is loading fine?

I stop now with the presumptions and wonder if you can post the output of cloudflare.com/cdn-cgi/trace. You might get routed via some odd route half across the globe (or “disc”, for our fellow flat-earthers :roll_eyes: :wink:), which could then explain why loading times are that high.

However, you said single PC. Am I to understand other machines on the very same network do not experience that issue? In that case it actually shouldn’t be a routing issue, assuming your machine is not using some sort of VPN and connects differently. It does not, right?

Hi Sandro. Thanks for your assistance. I always liked to imagine the flat earth was thought of as a floating triangle xD.

Yes, I get the same issues with performance for this forum (after unregistering the service worker of course, so the requests go to the network) though the FCP is not nearly as delayed, probably because the forum requires less work. But 1.78s content download for the 46kb html document. sitemeer.com is a little tougher to notice on, because it’s so darned slim. But I see some of the same patterns in the waterfall (987ms TTFB for the favicon).

I do not know which websites do or do not use cloudflare at large, but this is not a constant item browsing the web as a whole, no. Amazon, Google, etc. no issues.

Yes, this is only impacting one device on the network. 3 other computers and 2 smartphones on the network do not have the same problem. And no there is not a VPN in active use on the PC in question. Obviously something is unique about the PC in question (otherwise one would presume it would not have this problem) but it is not in the way it connects to the internet. At least not by intent.

And here is the requested trace:

fl=12f633
h=cloudflare.com
ip=2601:500:8200:af20:9ef:d827:7e46:438b
ts=1633715168.445
visit_scheme=https
uag=Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.61 Safari/537.36
colo=LAX
http=http/3
loc=US
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off

All right, we can probably safely assume you are not routed all across the triangle :wink: - you are in the US, right?

Thanks for your kind words on Sitemeer’s fitness, the meerkats are very proud of their 90s handcrafted HTML :wink: but a second for Favicon really should not happen either.

This is a tad odd, as it does not seem to be a routing issue and it seemingly is the only device on the very network. Have you ruled out any security software on that machine (including Microsoft Defender)? You said you tried other browsers, which ones? Firefox too? What about proxy configurations?

Thanks for following up on this Sandro! I am indeed in the US portion of the triangle. And the meerkats did well :grinning:

I had tried disabling the AntiVirus before, just now I’ve tried again without either the AV or Windows Defender, no luck.

I’ve never messed with proxy configurations before, but I went to check nonetheless and they were all set to default (everything off + empty, except “Automatically detect settings” was on.) I even tried with “Automatically detect settings” turned off for good measure and saw no change. Though I wouldn’t think there would be any impact. The PC in question is in a personal residence using generic Xfinity broadband.

The browsers tested include Chrome, Edge, and Firefox. I will note, and it only makes the thing more confusing, Firefox does perform significantly better than the other two, though it is still struggling. I’d approximate it loads resources about twice as fast.

The whole thing is just so darned puzzling. And Google has thoroughly let me down thus far.

Edge is Chrome these days anyhow and if Firefox performs better, that could indicate something about the proxy or SSL configuration, as only Firefox really comes with its own setup here, though you already checked the proxy as well.

So, even with Firefox it is noticeably slower than on other machines in the same network? Any other security software installed? That would be my closest guess, but of course without direct access to the machine it’s really rather a guess.

Any funny SSL configuration on there? A network policy maybe?

You said you checked proxies, but I’d really double check any additional security software or odd network configurations. If you can rule out all of that I’d probably continue on Reddit or StackExchange as there must be some local issue.

Generally speaking the topic would be a tad off-topic for here, as it does not seem to be Cloudflare related, but we could still play the game who(m) we gonna call and maybe @MVP has some more ideas as I am afraid the humble servant of the meerkats is out of ideas.

So that means no middle-boxes, using the default DHCP provided DNS, you haven’t “fixed” any settings on the CPE?

If you use PowerShell fetch/cURL the 10s JS file you mentioned above, does it still take 10s? Essentially, is there a problem with the networking stack on your device?

If you create a new profile/user on the device, is the problem the same?

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One more thing, try speed.cloudflare.com. The values are pretty inaccurate but I’d expect it to be lingering around modem speed as well compared to other non-Cloudflare speed tests. Is that true?

Thanks for your continued assistance to you both. I knew that it might be a long shot and that this was probably not standard-faire for this board. But seeing as so far I’ve only identified this issue with Cloudflare, I was hopeful someone maybe heard of something like it before and had some ideas.

Nope. Nothing in the middle, the PC connects directly to the provided wifi/gateway. And I haven’t configured and of the settings, port forwarding or anything of that nature. Truth be told, while I consider myself a good web engineer I’d make for a pretty poor networking power-user.

Creating a fresh user on the same box has the same problems when used in the browsers. As for the cURL test, it’s a little tough to be 100% confident because the individual resources have variances on each page load. Even just opening a single JS file via chrome that I viewed being problematic will not be too slow all of the time. Sometimes I’ll observe it in the 300ms range, and occasionally it will spike to 2+ seconds. It’s noteworthy that I haven’t been able to get the lone resource to approach the 10s range, so I would imagine the act of negotiating multiple resources simultaneously (as during page load) is substantially impacting the network behavior. All of that said, from what I can tell it looks like it’s pretty instant for cURL in WSL and Invoke-WebRequest in the Powershell. So they may not be impacted by the issue. Maybe writing a script to iterate a fetch req 10000 times and looking at the min and max and median would verify that for me.

The Cloudflare speed test appears to be in the same range as speedtest.net. A little slower, but same ballpark.

I realize that at some point I might have to just start killing tasks and processes one by one to try and figure it out… but if either of you come up with another thing to check I’d be glad of the advice.

In that case I’d try a download of a larger file and compare that to the other devices. If there’s no actual difference it will be browser related and that would either point at some system proxy (I know you mentioned it, but double double check that) or some obscure security software on the machine which takes the liberty to tell the browser what to do :slight_smile:.

And now your message just disappeared so I can only randomly respond to your speed test statement. If that actually worked fine, it just got more mysterious as that site should go via the same infrastructure as any other proxied site. Apart from the actual speed test, did the site itself load in a normal fashion?

I saw that it had disappeared as well, and I was very sad (and confused) about it, but it seems now that someone has rescued it from the aether. Thank you! :grinning:

I’ll try to run a test on a larger file tomorrow if I’m able. That’s a good shout out.

NGL, it’s a bit hard to analyze the network of the cloudflare speed test, given how much traffic it’s putting through. But the core of it seems to be fairly slim (perhaps meerkats were responsible :thinking: ). It actually seems like a lot of the fetch/xhr requests are pretty consistent, and I have no clue why, but that would explain why the reported speed is in the same ballpark. But I do see a bit of the same old curiosities as well. One of the page loads I got a 3.32s content download on the index.js file (142kb). And that darned favicon had a TTFB of 1.61s as well.