Just a "final" feedback, after I turned on "Low power mode" which from my understanding unloads the tabs from RAM, the issue hasn't happend anymore, even other apps wich seemed to lag stoped having problems, so my suggestion would be something like the extension TabWrangler that auto closes some tabs after a while, something like the ArcBrowser does(I only heard, didn't test it myself), personally I think that would be a better experience overall, still having the instant switch but with more controll over which tabs stay open/loaded into RAM.