On phones and tablets, RAM is part of the device hardware and generally not user-upgradable (despite jokes to the contrary). A quick check of the galaxy Note Pro shows it has 3GB built-in- quite decent actually. I'd suggest uninstalling that "speed booster" app or other "virus" and "task killer" apps-- Android isn't Windows.
It usually doesn't need extra stuff like that. Decent security/malware detection is already a part of Google Play, and those listed "features" raise alarm bells for me. I also saw reviews saying it contains spyware.
The truth is, you are making this harder than it should be. A normal Android user typically should never be concerned with manually quitting programs you are not using as new Android devices very efficiently manage their performance and kill background apps automatically. Similarly, you should generally NOT be emptying app caches manually, ever, unless a particular app is giving you problems- and certainly not "regularly".
In short, the stuff you are doing thinking you are improving performance is best left to the system, which can do it much more effectively and efficiently than you can. Android devices should be VERY easy to use with minimal maintenance-- please beware many 3rd-party apps that may lead you to believe they are necessary for improved performance. Task-killers and such may actually degrade overall performance as they waste memory and processing time interfering with thigns that Android itself is finely-tuned to do.
Perhaps the best "speed up" tip I can offer: disable/uninstall apps you don't use (some of which may be running in the background), especially bloatware and adware that are shoehorned onto your phone by unscrupulous wireless carriers. An even better alternative-- look into bloatware-free aftermarket ROMs if they are offered for your phone (the best ones cost nothing, by the way) or root your phone and remove that bloatware entirely from the system.
(Note: Originally posted this as a comment, but by request expanded it into an "answer")