How to determine the cause of the slow opening of pages in the browser?

Question

Browsers

I began to notice that sometimes some pages in the browser open for a long time (up to 10 seconds), including, for example, the router page 192.168.1.1 or other webmords on the network, pages of different sites.
Windows 8, Chrome browser, Eset, connected by wire to the router, Internet ping 3 speed 100/100, ping to Yandex or ping to the router at the time of long page loading - as usual, without breaks.
Prots/memory/disk - normal behavior.
Disabled antivirus and firewall to no avail.
Dns were Google, put Auto.
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How can you understand the cause of the brakes?
Is it possible that a sip phone with a radio base has appeared on the local network? Because I didn't notice this behavior before.

Answer 1

In Chrome, press F12, go to the Network tab, check the Disable cache checkbox and refresh the page - you will see what exactly is loading for a long time.

Answer 2

The site's servers may be overloaded.