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Lately i have seen high time to first byte for my sites.

Most of the time it is by javascript. A test at webpagetest.org usually shows like....

URL: http://example.com/ Loaded by: http://example.com/some-kind-of-javascript.js

When i remove that javascript then anothe javascript appears in that place.

What does loaded by exactly mean??

Check example test result....

https://www.webpagetest.org/result/190729_JY_cb028989b0f44671fba830c9eaca29d7/1/details/#waterfall_view_step1

kpmrpar
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I'm not sure why you think it's Javascript that is the problem? It looks to me like it's the initial HTML that is causing the problem.

Time to First byte for a resource is the time take from after sending the request (e.g. GET /) until it receives the first byte back. It excludes the DNS lookup, TCP connection and SSL handshake time, so really is a measure of the time take to start receiving that resource. Note that the "first byte" time at the top of the waterfall is the full end to end time, including DNS/TCP/SSL and any redirects, but the TTFB for each resource this is split out more.

I don't know how your home page is created - I would guess it's not a static page so whatever is generating this (PHP?) is taking too long. Whether this is due to bad backend code, an under-resourced server, a slow database, or something else is impossible to say from the outside. I would suggest getting in touch with your hosting provider and/or reviewing your code and server.

Barry Pollard
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  • My site is in php wordpress. But the same is happening with sites hosted at different place. Check this https://www.webpagetest.org/result/190729_TG_b742c2078c263f011b79d49d663cc6a9/1/details/#waterfall_view_step1 – kpmrpar Jul 29 '19 at 14:05
  • On that link TTFB is 548ms. On your first web page test link TTFB is 14587ms. That's a heck of a difference! So I don't agree the same is happening there. – Barry Pollard Jul 29 '19 at 15:53
  • Yes agreed (i tried default theme and ttfb is 700ms). But there is no way i can change theme. So i havve to find a way out to solve this 'loaded by' puzzle. @Barry Pollard – kpmrpar Jul 29 '19 at 20:18