Why Is Switching Over Multiple Tabs In Firefox So Slow

My problem is just the slow switching over multiple tabs in Firefox. Each time I go to another tab it takes a while (sluggish), or you can say the ‘click’ on the tab takes time to happen. The rest Firefox is working perfect in speed.

Don’t know how to solve it, followed all the steps on the MakeUseOf Firefox Speed Up Guide, still having same problem.

Second problem is how to stop the automatic ‘Get add-ons’ which can be seen in Tools>Add-ons>Get add-ons. Can anyone help please?