iMac 10.1, OS X 10.7.5, 4 GB RAM, 201 GB free on 999.35 GB HD, gets slower the longer I use the Internet; very noticeable with online browser game Forge of Empires. Turning iMac off and restarting it brings it back to full speed for an hour or so.

I don't do gaming, but my guess is you need more RAM - 4gb is not a lot for processor/graphics intensive actions.

Macsales and Crucial are good places to buy:

http://eshop.macsales.com/shop/apple/memory/iMac

http://www.crucial.com/

1st thing : from my point of view upgrade your mac os to latest version.

(their is mac os x mavericks from apple its free for upgrade so download it and install it.)

(https://itunes.apple.com/in/app/os-x-mavericks/id675248567?mt=12)

2nd thing : then upgrade your all browser plugins to latest version.

3rd thing : and use ccleaner to keep clean your mac from junk data or other unuseable data that are created.

(http://www.piriform.com/mac/ccleaner)

4th thing : verify and repair your disk permissions with the use of disk utility or ccleaner

i am sure your computer recover speed.

🙂

3rd thing : and use ccleaner to keep clean your mac from junk data...

I don't want to start an argument, but this is bad advice. DO NOT ever install apps that claim to 'clean up', 'enhance', 'boost', 'optimise', etc. your Mac.

Apps that make these claims have the potential for deleting essential system files, possibly rendering the Mac inoperable.

Mac's are very good at doing their own housekeeping.

Yeah I am sorry ,but I forget to type (optional).

The most important thing to remember is gaming is very intensive on resources. It is a good idea to Max out your Ram. It is imperative if you want absolute best for gaming. SO that would be the very first thing I would do. Max out your Ram and use.. Crucial or OWC.