(Also, is iPhoto supposed to be a heavy app? It makes my macbook pro quite hot and the fans run quite fast so that I can hear them)
That doesn't sound right.
As a Test:
Hold down the option (or alt) key and launch iPhoto. From the resulting menu select 'Create Library'
Import a few pics into this new, blank library. Is the Problem repeated there?
I had suspected the Library as the cause or a bunged up cache file, but that rules both of those out.
Back up and reinstall.
To re-install iPhoto
1. Put the iPhoto.app in the trash (Drag it from your Applications Folder to the trash)
2a: On 10.5: Go to HD/Library/Receipts and remove any pkg file there with iPhoto in the name.
2b: On 10.6: Those receipts may be found as follows: In the Finder use the Go menu and select Go To Folder. In the resulting window type
2c: on 10.7 they're at
A Finder Window will open at that location and you can remove the iPhoto pkg files.
If you purchased an iLife Disk, then iPhoto is on it.
If iPhoto was installed on your Mac when you go it then it’s on the System Restore disks that came with your Mac. Insert the first one and opt to ‘Install Bundled Applications Only.
If you purchased it on the App Store or have a Recent Mac you can find it in your Purchases List.
I am new to a mac, but should this fix the issue of heat as well?
When Iphoto is running the computer gets quite hot with the fans running...
I went to the Apple Store to check if everything was normal, and they said it was all fine...
Is there a way to check if your computer is running properly?
Thank you for your help