Mountain Lion and speed

Your machine is most likely starved for RAM. 2GB of RAM is the absolute minimum for Mt. Lion, I would recommend upgrading the RAM to 4 or even better 6GB of RAM to improve performance. OWC makes a 6GB kit that you can find at www.macsales.com.

Go to Crucial or OWC they are both great vendors and have gaurenteed RAM for your system. It's the easiest thing to do for your iMac. While you have your old RAM out and the grill off

As old as your iMac is, have you cleaned out the dust? Dust buildup can lead to over heating issues. Remove any and all things plugged into it including the power cord, Remove the RAM access grille. Vacuum all openings starting with the RAM access area (air intake). Vacuum all ports and plugs, DVD slot and the opening across the top of the rear of the body. Blow compressed air through all your openings and vacuum again to remove any dust you loosend. Reinstall the RAM grille. Plug in the keyboard and mouse if not blue tooth. Insert power cord...

You are now in a perfect position to do a

SMC RESET

http://support.apple.com/kb/HT3964

• Shut down the computer.
• Unplug the computer's power cord and ALL peripherals.
• Wait 15 seconds.
• Attach the computers power cable.
• Wait another 5 seconds and press the power button to turn on the computer.

It is the 5 second timing that initiates the reset.

Here is a link to a Widget to monitor your temps and other operations:

http://islayer.com/apps/istatpro/

Why is the RAM from Apple so much more expensive than the ones offered by Amazon

Because their main focus is on on selling consumer products and software.

Other businesses like OWC focus on being competitive with peripheral components like RAM . That is not Apple's main game. Everyone has their (specialised) niche, according to their needs (business model).

But Jeffrey, I think an intelligent man like you already knew this. 😉

Your model can have RAM added to it up to a maximum of 6GB (Actual), though doubling it to 4GB would be a noticable improvement. Worth doing, especially as it is not so expensive these days.

It's also so much more expensive because they can get away with it. People think they have to buy Apple RAM. A CR2032, which is a widely available Lithium button battery used for the PRAM chip in Macs, costs maybe $5 tops in a drugstore. From Apple, it may be five or six times that.

When Apple specs out a unit they frequently "lowball" their stats. As an example their latest iMac is rated by Apple to only accept 16GB of RAM but lots of people are running 32GB. Crucial has a system scan that will look at your computer and tell you what their recommendations are, they guarantee compatibility.

Yes in this case Apple is wrong!

I just checked OWC and they're sold out of the 6 GB RAM upgrade kits.

Contact them to see when they expect to replenish. They have online chats and also you can email or phone them.