I have a Galaxy Note II and it's too slow due to low memory, I bought a 16 GB memory card and it still is slow, what to do?
The speed of your device relates to the RAM not ROM. RAM of NOTE2 is 2GB and RAM is not expandable. RAM is the memory where all your foreground and background process resides. If RAM usage in your device is very high, uninstall or disable unnecessary applications. And install a Task Killer and schedule it in crazy mode at every half hour. It may increase the speed of your system.
You can manually clear your ram from task manager. Long press home button then tap on left most option which is task manager there select ram tab and tap on clear Memory.