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Need help optimizing site with a LOT of traffic. Keeps crashing. WordPress


Recently launched a WP site that is getting a lot of traffic.

The site is crashing quite a bit and according to my hosting, it is due to excessive PHP requests, which go beyond the allowed limit.

Among the obvious optimizations I am currently performing on my website to hopefully improve its performance, they pointed out at an error that keeps showing up in their error logs.

It's the following:

PHP Warning: Cannot modify header information - headers already sent by (output started at /home/elvocero/public_html/wp-includes/functions.php:1110) in /home/elvocero/public_html/wp-includes/functions.php on line 1095

I have searched for a couple of hours, but haven't really gotten to the bottom of it, since it's referring to a core WP file, and not a plugin, or anything that could have been wrongfully edited.

I need help figuring this out.

Website is:

Let me know which other information you need to help me debug this.


Answers (6)


Arnav Joy answers:

open your functions.php file and at top of it write following.


plaxplax comments:

or my theme's functions.php?

Arnav Joy comments:

theme's functions.php

plaxplax comments:

thanks. made the change. give me 24hours or so and see if it's fixed.

Arnav Joy comments:

ok , good to hear that it is fixed , let us know if you have any problem.

plaxplax comments:

it isn't fixed yet. i will monitor it and see if i get the error again or not. give me til tomorrow.


Hariprasad Vijayan answers:


You may have blank spaces or blank lines before an opening <?php tag or after a closing ?> in your php files. Remove those blank spaces/lines.

Check this link :


Abdelhadi Touil answers:

Do you use a Cache plugin or not?
You should use one, and you should optimize your database and delete revisions because they make database bigger.
You can test using Quick Cache plugin as it's easy to use:

and it's good to read and use plugin described here:

Good luck!

plaxplax comments:

yes, I use Super Cache.


phppoet answers:

PHP Warning: Cannot modify header information - headers already sent by (output started at /home/elvocero/public_html/wp-includes/functions.php:1110) in /home/elvocero/public_html/wp-includes/functions.php on line 1095

although this error directs you to wordpress core , in most of cases such a error is caused by a some plugin. You should disable all the plugin first and then enable each one by one and check the error to get the conflicting one .



Francisco Javier Carazo Gil answers:

If your host allow you to use a it, use Varnish. This is a cache in the server level, so much better than WP Super Cache (you can use both at the same time). It is a proxy software and your site will be able to support much more traffic and the speed will be increased a lot.

Try it or talk with them if you can:


Bob answers:

is it fixed?