There seems to be a lot of confusion in this topic.
All Macbook Pros in 2010 shipped with 4GB or more of RAM. Unless someone took out a stick of RAM (unlikely), this macbook is probably:
A 2010 model Macbook Air. These machines shipped with Core2Duo CPUs running at sub-2Ghz speeds. They were usually configured with 2GB of RAM, but could be upgraded to 4GB at time of purchase.
These machines CANNOT have their RAM upgraded later in life as they are soldered to the logic board.
Additionally, those of you who are recommending an upgrade to an SSD, these machines came with either 64GB or 128GB mini-sata SSDs built in.
This means that although it has very little RAM, it won't be too bad because the machine will be able to utilise free space on the SSD as swap.
So OP:
1. Verify that you have the 2010 model Macbook Air (3,1)
2. Make sure you have at least 10GB free on the SSD so that the machine can utilise swap space.
3. Try a clean installation of the OS. You can do this by booting to recovery mode by pressing down Cmd+R during start up.
4. If absolutely neccesary, downgrade to Snow Leopard, which is what the device originally shipped with. You will need to use the thumb drive that came with the computer since the Macbook Air does not have an optical drive.
I hope that helps. If you have more questions just reply to this post.