Ok if free ram getting low? The problem is I don't want android kill my background apps like viber, line those apps.. I do have many apps running in background.. Viber, line, wechat, whatsapp, hangouts, Skype, messenger and etc.. So what phone are u using?

Free ram for what i mean here unused memory only. My intention thought very simple. I don't want android so auto kill my backgrounds apps due to low memory. If I'm using 1gb ram phone, I didn't mean its lag or not good.. Just when low free RAM, it's does lag and then a while android kill my apps. That's why I said 2gb ram is reserved for future use..

Try install as many as social messaging apps in ur S2 and Z. So u will understand it. Let 3G or wifi make all apps active all the time. After that, try use browser to surfing with those apps running in background. See whether the keyboard will lag a while and then smooth after some apps closed by android.

Active here mean all social apps with active account. Viber, line, wechat, whatsapp, Skype, fb messenger, fb. These 7 apps enough. Try check the free ram left in system.  After that, open chrome or any browser and try surfing.

We are different.. I didn't use chrome coz I knew the issue u mentioned. I'm using Firefox. I'm not engineer, I'm just a normal user with need some social apps to contact with my friends from worldwide. I do have data plan in my phone so I wish to make all apps active all the time. What for if I just keep close my apps mostly only use when I need. I just want better user experience here.. I don't want suffer on laggy or low memory problem. Ok. That's all.. Finished. U continue ur engineer life, and I continue my normal users life.. Haha..