Hi I purchased my first Mac, a 2011 27" iMac about 9 months ago. One of the first things I noticed was that relatively small apps such as Mail, Calendar, App Store, etc. would take a few seconds (about 2-5) to open. I assumed that this was normal for a Mac until a few weeks ago when I used an entry level Macbook Pro 13" and noticed how snappy it was. Another thing I noticed was that my iMac's hard drive would constantly be making a noise when opening an app, browsing the web, using finder, etc. Then a few days ago my mission control animations started slowing down. I tried everything to fix it including PRAM reset, disk permissions, etc. Nothing worked and it annoyed me immensely so I decided to erase the OSX partition and reinstall Lion from internet recovery. After doing that mission control was fixed but strangely, the entire machine ran A LOT faster. Opening Mail now only takes a split second. Browsing the web doesn't make the hard drive go crazy anymore. And I don't have to wait 10 seconds for an MP3 folder to open. So my question is, what could have possibly caused the iMac to struggle from the very first day? I would like to find out in case it's something that could happen again so that I may avoid it. The hard drive is a western digital, not one of the seagate hard drives that would have been recalled. I know it's a strange question but any advice would be appreciated. Could Lion have been installed incorrectly at the factory?