I have installed firefox 3 hours ago , I want to download something . but in firefox download become very laggy . i have good internet about 60 mb/s and the servers i am downloading are very fast always , amd only one tab open , only firefox is running system is also on 50% percent memory , and it is happening on every website ,about 200 kb/s speed i have 2 extentions "Ublock by Ramond Hill and Sponsor block " and 1 theme of dark firefox