My mac is slow.

How do we even know if there is a problem. If you put in a new drive, then you have to reinstall OS X or clone your old one to the new one.

About OS X Memory Management and Usage

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.

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.

Hello karenfrombaltimore and welcome to Apple Support Communities,

First tell us your exact MBP, size and year released, operating system, current hard drive and current RAM.

"since i'm replacing the storage, do i have to re-install osx?"

No you would simply clone your current drive onto the SSD.

Typically using Carbon Copy Cloner or Super Duper.

Also I always buy from OWC:

http://eshop.macsales.com/shop/SSD/OWC

Never a compatibility problem and dead easy to install.

I upgraded my 2011 MBP 13" with a 120 GB SSD and bumped the RAM to 8 GB. Photoshop CS 6 starts up in 3.4 seconds and Word 2011 in 2 seconds flat. My wife complained that her 2012 Mini was sluggish so I did exactly the same thing to her Mini.

Happy wife, happy life and like new MBP!

No. It will be a bare drive that must first be partitioned and formatted in order to install OS X. I answered this in my first reply. If you don't wish to clone your old drive to the SSD, then you will need to prepare the drive and install Snow Leopard from the original disc that came with your computer.

Clean Install of Snow Leopard

1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came

with your computer. Insert the disc into the optical drive and restart the computer.

After the chime press and hold down the "C" key. Release the key when you see

a small spinning gear appear below the dark gray Apple logo.

2. After the installer loads select your language and click on the Continue

button. When the menu bar appears select Disk Utility from the Utilities menu.

After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive

size.) Click on the Partition tab in the DU main window. Set the number of

partitions to one (1) from the Partitions drop down menu, click on Options button

and select GUID, click on OK, then set the format type to MacOS Extended

(Journaled), then click on the Apply button.

3. When the formatting has completed quit DU and return to the installer. Proceed

with the OS X installation and follow the directions included with the installer.

4. When the installation has completed your computer will Restart into the Setup

Assistant. After you finish Setup Assistant will complete the installation after which

you will be running a fresh install of OS X. You can now begin the update process

by opening Software Update and installing all recommended updates to bring your

installation current.

Download and install Mac OS X 10.6.8 Update Combo v1.1. You can now download Yosemite from the App Store and install it.