Two Plugins vs. Single Plugin

There is. Having more then 3 plugins will slow your website and destroy seo of your website. Average plugin done by average plugin developer slows website for 6-12% - most of those websites are rated RED by Google Pagespeed. A lot of plugins for Wordpress themes are not optimised, and more and more developers are refusing to do it, which leads an owner of the website to spend more money on SEO then usually if developers were created a green design website. I strongly suggest to avoid using custom fields plugins, it is better to handcode custom fields through functions.php into the theme on which you are working, and leave space for some other plugins that you can't avoid.

@Zeljiko so 3 plugins that say hello world will shlow down your website and destroy your SEO? That is far from true. It really depends on the plugins you use. A site can be fast and have 100 plugins. I have seen fast sites that had 40+ plugins. I have seen sites that are slow with 1 plugin. Having a lot of plugins spread out vs putting code in functions.php makes your app more modular.

To prove my point run SEO analyzer and Google Pagespeed. Does not, more then 97% of plugins are not optimised at all. Even plugins for speeding the website that mess with htaccess. So users ends with this:

1. install all bunch of unecessery plugins, your website crashes into red zone TESTED WITH GOOGLE DEV TOOLS.
2. Install w3Cache plugins, they only does minifing and pretty much create messed up htaccess file, but you will still end up with 6% - 14% less from 100% of full optimisation and all standard rules applied, because plugin that minifies is not optimised.
3. Yoast for SEO same thing.

If you want green rated website, integrate your own plugins, write your own htaccess and stick to max 3 third party plugins. You don't need gallery plugins, you don't need lightbox plugins, you do not need form plugins, and you def. do not need SEO plugins and wordpress frameworks for RWD, because all of that is easely done through functions.php and using logical structure of layouts and is not hard to learn or understand - if you know php.

This is based on one year testing and observing the impact of wordpress plugins on website performances - the reaserch I did back on the college while I was still a student. If you want to check it out, feel free to do testing by yourself, you will get the same result, completly the same. ;)

Yes, makes your website more modular, yet search engins have their last world. Modular does not mean a thing if your website is trashed into red zone and put at the end of a search results that asks your clients to invest more into online marketing then they would usually have to. There are plugins that are important, 90% of them are not and are poorly developed and optimised.

All this you also have explained by Google dev team in even more details under one of their free seminars.

@zeljko your research is coming from you. All these numbers you are thowing out are thin air. You can have 100 plugins and it could be faster then 1 plugin.

Noobs put all their code in functions.php . That is not modular and gets messy fast. There is no noticable performance difference if the code is in a plugin or in the functions.php theme file.

w3 cache does not mess up your .htaccess file. it makes changes to it and they could mess it up. If you do not know what .htaccess rules do you probably shouldn't be the one configuring caching and should find a professional to help you.

Yoast is garbage as of 3.0 and has always been bloated plugin.

Noobs?! Are you a child?! There is something called request, request once and so on... It's standard call for summing different files (actions and filters) under one, since all files needs to be appended through functions.php to take the action. Basics of Wordpress?! How you don't know that?!

To prove my point, write function in functions.php that will do the same as plugin you are testing. Turn off the plugin, run your website through google dev tools, after getting the first results turn off the functions.php function and turn on the plugin, run the test again. Obviusly you don't know how plugins are pulled in your theme and you do not understand requests and what impact they have on loading your websites. Do this testing that I ask you too. You will be stunned how wrong you are. ;)

I am professional and I understand every single line in htaccess, wierd you do not since you acted like you know it very well. That's why I know what cashe plugins do to it, because I write my own htaccess files that have better impact then any plugin right now on the wordpress market, and such kind performances can only be done by hand, not by 3d party general plugin, which every web developer knows - at least professional one.

Also I would like to point out something else, since you are not also familiar with it, it considers amount of redirections and requests, more requests for different resources you have through your code it will slow your website - and there is far more bad structured websites and plugins then those that are done correctly. I rest my case here. Do the testing.