I'm running Firefox 5.0.1, and along with some plugins I need (Flash Player, Quicktime, Flip4Mac, Java, Silverlight), there are a few I don't, such as the iPhotoPhotocast and Microsoft Sharepoint plugins. Are there any speed/memory usage benefits to disabling them or removing them from Library/Internet Plug-Ins?
I am not 100% sure, but I believe plug-in's only become active when they are required. Like a web page that has a specific format, the browser will then go through plug-ins to see if any are compatible. They also generally do not take up that much memory (maximum a couple MB). I highly doubt you would see much of a performance upgrade by removing them. Probably have more of an inconvenience of not being able to open all file types online.