There has been some interesting discussion on how many plugins you should use on your WordPress blog, and whether that number contributes to any problems along the way. The fact of the matter is, it’s really hard to say.
In most situations, using an excessive amount of plugins won’t cause any problems, but plugins use memory when they run, and shared hosting provider love to limit the memory that you can consume at any given moment. If you’re running into memory errors, there are a few things that you can try, but you should probably consider using less plugins or moving to a better host. Outside of hosting limitations, the number of plugins doesn’t play much of a role. We use 36 plugins here, and I have worked on a blog before that used 82, both without issue.
If you’re running into other errors, that’s more than likely just one plugin with nothing to do whatsoever with the amount of plugins you’re using. As long as you continue to use the offending plugin, you’d see the same errors with 2 plugins as you would with 200.
The real question here is, do you need all of those plugins? It might be time to do some spring cleaning.
Are you using a plugin to loads a chatroom in your sidebar? Has that chatroom been used once in the last month? If not, it’s probably time to get rid of that plugin. Do you use a plugin to display a gallery on your blog? WordPress has had built-in gallery support for over three years, so it might be time to get rid of that plugin too. Do you use Simple Facebook Connect to automatically post to Facebook, but use another plugin to add a Facebook Like button to your posts? Well, Simple Facebook Connect can add a Like button too, so you might as well get rid of that second plugin. And, like Simple Facebook Connect and Jetpack, there are plenty of good plugins out there which can probably take the place of more than one plugin on your blog.
The number of plugins you use really doesn’t have much of on an impact on your blog (unless you’re running into hosting limitations), but it can’t hurt to clean things up once a year or so.