: Would parallelizing downloads across hostnames improve TTFB? I am getting very high TTFB (Time To First Byte) about 2.6 to 3 seconds, I have very high number of images on my pages. I want

@Yeniel560

If you are using Apache, check your KeepAliveTimeout value in apache2.conf. When a client is loading multiple files from the server, the connection is normally reused for each, but it looks that's not happening in your case.

The default of 5 should be enough, but try 8 or 10 as well.

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@Dunderdale272

TTFB is totally dependent on server load and available bandwidth.

If your server is heavily loaded (lots of requests per second) then your TTFB will rise exponentially. This effect is multiplied by lower server spec and available bandwidth.

Spreading the load over multiple sub domains may or may not have any effect, this depends on how you actually technically do it:

IF you use multiple sub domains linked to the same server, then expect little or no difference.

However if you spread this load over multiple sub-domains pointing do different servers then i could see potential for a lowering of your TTFB - this is how CDN's work.

HOWEVER it is likely that this high TTFB is caused by another factor such as scripts running on every page load - i would investigate the cause before trying to solve it in this way.

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@Carla537

Adding MORE (sub)domains can only INCREASE this value because the computer/visitor has to do another lookup to resolve the domain to an IP.

You'd be better off trying to find out WHY you have a high TTFB.

From Wikipedia: "Time To First Byte or TTFB is a measurement that is often used as an indication of the responsiveness of a webserver or other network resources. It is the duration from the virtual user making an HTTP request to the first byte of the page being received by the browser. This time is made up of the socket connection time, the time taken to send the HTTP request, and the time taken to get the first byte of the page."

...made up of the socket connection time, the time taken to send the HTTP request, and the time taken to get the first byte of the page


Do a test on tools.pingdom.com/ to see which part(s) of this is taking the longest.
Post some details about it, so others can help you. I can't say much about exactly how to fix it because I don't know what the problem is exactly.

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