When new WordPress users discover plug-ins, their first instinct is to load as much free goodness as they can onto their sites. After all, if one plug-in is great, two dozen must be mind-blowingly fantastic. Before you get carried away, it’s worth pointing out the many reasons you don’t want to install every plug-in you find:
• Performance. As plug-ins use PHP code to carry out their tasks. The more plug-ins you activate, the more work you’re asking WordPress to do. Eventually, this work might add up to enough of an overhead that it begins to slow down your site. The plugins that do the most work (and are thus the most likely to hinder site performance) include those that back up your site, log your traffic, search for broken links, and perform search-engine optimization.
• Maintenance. The more plug-ins you have, the more plug-ins you need to configure and update (when new versions come out). It’s a relatively small job, but pile on the plug-ins and you might find yourself with some extra work.
• Security. Plug-ins can have security holes, especially if they’re poorly designed or out of date. More plug-ins can mean more risk.
• Compatibility. Sometimes, one plug-in can mess up another. If your site uses a huge thicket of plug-ins, it’s difficult to track down which one is at fault. You need to resort to disabling all your plug-ins and then re-enabling them one at a time, until the problem recurs.
• Obsolescence. Often, plug-ins are developed by helpful people in the WordPress community who need a given feature and are ready to share their work. But there’s a downside to this development model—it makes it more likely for an author to stop developing a plug-in (for example, when he doesn’t need it anymore or when he just doesn’t have the time). Eventually, a new version of WordPress may break an old plug-in you depend on, and you need to scramble to find a substitute.
The best way to avoid problems like these is to use popular, regularly updated plug-ins, make sure they’re always up to date, and keep the number of plug-ins you use small.