MacBook Pro 13" (2012) non-retina ram upgrade.

Question

Will upgrading my MBP 13" from 4GB to 8GB will make a big difference ?
MBP does get slow at times and i do tend to use 4+ apps most the time.
Will it boost my boot up time too ?

Answer 1

Adding RAM only makes it possible to run more programs concurrently.  It doesn't speed up the computer nor make games run faster.  What it can do is prevent the system from having to use disk-based VM when it runs out of RAM because you are trying to run too many applications concurrently or using applications that are extremely RAM dependent.  It will improve the performance of applications that run mostly in RAM or when loading programs.
Does it help to have more RAM? Usually, "yes", if you are running out of RAM during use. You may find that the computer seems faster, but this is because memory shortage is bogging things down.
Using Activity Monitor to read System Memory & determine how much RAM is used
OS X Mavericks- About Activity Monitor
Understanding top output in the Terminal
The amount of available RAM for applications is the sum of Free RAM and Inactive RAM. This will change as applications are opened and closed or change from active to inactive status. The Swap figure represents an estimate of the total amount of swap space required for VM if used, but does not necessarily indicate the actual size of the existing swap file. If you are really in need of more RAM that would be indicated by how frequently the system uses VM. If you open the Terminal and run the top command at the prompt you will find information reported on Pageins () and Pageouts (). Pageouts () is the important figure. If the value in the parentheses is 0 (zero) then OS X is not making instantaneous use of VM which means you have adequate physical RAM for the system with the applications you have loaded. If the figure in parentheses is running positive and your hard drive is constantly being used (thrashing) then you need more physical RAM.