MacBook – How to do with the original RAM after an upgrade

As Apple states in the link you mentioned:

For best performance, fill both memory slots, installing an equal memory module in each slot.

• Get one more 4 GB memory stick and install it.
• There is no need to throw your existing one and get two of the same kind, since memory chips are rigorously tested for compatibility, especially if you buy from a seller like OWC - MacBookPro memory or DataMem - MacBook Pro memory.
• The memory sellers would also provide you with the right memory for your system.

Mountian Lion uses 2GB RAM, Mavericks 4GB. Windows 7 2GB... I don't want to know what the new Yosemite is going to gobble (especially a bad move of Apple soldering RAM t logic board in new MacBooks... the idea of plug-in chips in soldered chip holders would have been a better solution if RAM cards were omitted), and avoiding it because of this issue and don't like its GUI design, which would put me off from the new features that are impressive...

I had a late 2008 Mac which was upgraded to 8GB, but still ran Mavericks slower than Mountain Lion and had to downgrade it so it can perform better, perhaps because Mavericks was designed specially for Retina based computers, which have a higher resolution. I now have a new Macbook Pro Retina with Iris Graphics,running mavericks. and is 8GB. It is always a necessity to have a computer that has its operating system using half of the physical memory for performance. It puts less strain on on the machine, and that free RAM would help with your creativity in photoshop, video editing, music creating and more... Logic and Garageband tend to spaz out when there is no free memory. Then if you thinking that a SSD would make virtual memory perform better, yes it would, but the downside is, continuous paging on your drive would decrease its estimated lifespan with wear and tear. Where paging is supposed to be only on occasion when your work maxes out physical RAM, not every time you use your machine. I would recommend a downgrade to Mountain Lion, until you have the plans and resources to get a new computer.