I saw a question from someone this week asking about plugins and whether they slow down site load times.
The answer is yes – they can.
And there are other things to remember too: they can clash with other plugins, your theme or even WordPress itself.
So what’s the best number of plugins to have on a site?
As a rule, the less plugins you have the better.
But it’s not quite as black and white as that, because it depends on which plugins, and how they work.
Some plugins need to access other sites in order to do their stuff. And if the site they’re accessing has problems or is down that can create any number of problems on your site.
For example, I used a related sites plugin for a while, but to do its thing it needed to access another site containing a central database of blogs.
After installing it I started getting PHP errors when I was trying to publish new articles. Not every time, but on many occasions. And the post publishing time was noticeably longer.
When I removed the plugin all those problems immediately disappeared and have never returned.
I wrote a post here about how a contact form plugin was preventing one of my clients from inserting images into posts.
On those two occasions plugins were clashing with WordPress itself.
They can also clash with themes and other plugins.
So I review plugins very carefully before adding them.
How do they work? Is the information they access on my site or another site?
I also have a development site and I test all plugins on that before ever letting them loose on my production site.
That related sites plugin I referred to above, by the way, tested OK on my development site and, initially, it worked fine on my production site.
So even if a plugin tests OK it can still cause problems later, particularly if it needs to access another site.
I suspect the problems it caused on my site came from the other site, not the plugin itself.
Plugins add overhead to your site and can slow down site load times, particularly plugins that need to access other sites, like Share This and Related Sites type plugins.
Review plugins carefully before installing them: What benefit are you expecting? What information sources do they access? How do they work?
Don’t install plugins that duplicate functionality. I read one post in which the writer had both the Platinum SEO pack and All-in-one-SEO-pack plugin installed.
The less plugins you have the less they’ll slow down your site load times and the less there is to go wrong.