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Author Topic: Websites slow start  (Read 2522 times)

Weaver

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Websites slow start
« on: March 25, 2017, 12:45:46 AM »

Websites seem to be taking slightly longer to open up compared with the usual. Speed tester speedof.me shows good numbers 7.55 / 0.88 Mbps. I wonder if I am missing anything. Anything that could affect TCP slow-start adversely? Increased latency - can't see it, latency minima look normal on all three lines. Absolutely zero packet loss (apart from when it is necessary).
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burakkucat

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Re: Websites slow start
« Reply #1 on: March 25, 2017, 09:18:11 PM »

Is it a general slowness or only with certain websites?
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Weaver

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Re: Websites slow start
« Reply #2 on: March 26, 2017, 12:32:25 AM »

Seems to be a general thing. Facebook and Kitz. Today is much better. I'm just trying to assemble a mental checklist of things that might affect 'responsiveness' in terms of the web user experience but which would not show up on continuous bulk speed-tester-type testing.
« Last Edit: March 26, 2017, 02:32:35 AM by Weaver »
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Chrysalis

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Re: Websites slow start
« Reply #3 on: March 26, 2017, 02:22:55 AM »

Sites with light content such as kitz performance will be mostly unrelated to what you see on speedtests, e.g. I can see loading this post the throughput was very briefly spiked at a massive 89kB/sec.

So think of base latency affecting DNS lookup performance as well as TCP connection setup time.
Speed of the server(s) hosting the content you accessing.

Of course on heavier sites such as flickr, then the speed of the line plays a much more important role.
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Weaver

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Re: Websites slow start
« Reply #4 on: March 26, 2017, 02:38:09 AM »

DNS is a good point. I am not sure how the visual feedback in Safari works, but the progress indicator going from left to right to indicate page load seemed a bit sluggish compared to usual. About a half second or more whereas normally you can hardly even see it.

Anyone know if DNS is included in that animated display, or whether the DNS lookup happens before the animation even is allowed to start? Asking a bit much I know. I can check DNS servers response times somehow I suspect, can at least ping them which is not at all the same thing. And I can compare against the excellent OpenDns and google ones.
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Chrysalis

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Re: Websites slow start
« Reply #5 on: March 26, 2017, 02:54:05 PM »

Open up developer mode in the browser, both firefox and chrome have this, then you can see the performance data on how the page loads, dns lookups, each object etc.

Most of the time if I see a delay prior to loading a page its either a dns lookup issue or the server hosting the content been slow to respond.   Remember before the hosting server can respond it usually has to process backend data such as compiling php, database lookups and so on.

Modern protocols like http/2 aim to speed things up e.g. it cuts corners on the session setup and allows more parallel loading of resources.

Delays while pages are loading is 90% of time due to tracking crap, visit e.g. a newspaper website and its not unusual for it to be loading up 10+ domains to load up one page each of course which needs a dns lookup and sessions been created, 80% of which is tracking/ad related.  Some sites also use a misguided principle based on old browsers like IE6 that its better to deliberately split content up across different hostnames, but the reality is that will increase dns lookups and session setup requirements.
« Last Edit: March 26, 2017, 02:58:27 PM by Chrysalis »
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Bowdon

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Re: Websites slow start
« Reply #6 on: March 28, 2017, 12:22:09 PM »

DNS Benchmark is a good free program: https://www.grc.com/dns/benchmark.htm

I've used it and changed DNS servers a few times. You set it going and dont use your connection and it'll go through all available dns servers and pick the fast one. I know the BT ones arent that fast. I usually end up using google.
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kitz

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Re: Websites slow start
« Reply #7 on: March 28, 2017, 06:28:29 PM »

Just noticed this.    There appeared to be a problem with [google] DNS on the 25th of March.   I was having problems with sites being slow to resolve... in fact I posted about it here

https://www.facebook.com/Kitz.co.uk/photos/a.301170340021205.1073741825.153712088100365/828814340590133/?type=3&theater

It cleared for me as soon as I swapped to a different DNS server.
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burakkucat

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Re: Websites slow start
« Reply #8 on: March 28, 2017, 06:38:33 PM »

There appeared to be a problem with [google] DNS on the 25th of March.

How odd. I make use of Google's public DNS servers and did not notice anything untoward last Saturday.
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Weaver

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Re: Websites slow start
« Reply #9 on: March 29, 2017, 12:46:09 AM »

I was using Andrews and Arnold's two DNS servers. I had never thought about this option. I could obviously ping them but that's not really quite good enough, really I could do with a tool to make high precision measurements locally.
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