What you can do is go through the list in add-ons periodically and remove any that you don't really use/need anymore. I just did that the other day and removed 3 that I'd installed to try out. They sounded good at the time but then realized I didn't really need them. I disabled them first and then used FF for awhile to make sure everything looked and acted normal for how I've been using FF. After a couple of days of doing things with FF and realizing that the disabled function was never called upon, I deleted them for good.I have 20 active, it doesn't seem different from when I had none, but if I find more that I want should I disable some?