New iMac hangs when flicking through photos on iPhoto

My new iMac seems to struggle with flicking through photos on iPhoto.

These are 20MP RAW files, but after flicking through about 7 or 8 I get the 'beach ball' for a few seconds and then it takes another few seconds before it is ready to go again.

The iMac is a 3.4 I7/3TB Fusion/680M config and I have tried this with the iPhoto library on both the internal Fusion drive and a USB3.0 external.

I have had the opportunity of trying two identical machines side by side and neither could do this. I am sure I didn't have the same problem with by 2008 iMac with a Core 2 Duo!

 

Perhaps. It was the only box I left unticked because I planned to upgrade it using thired party stuff later on.

This still has 8GB compared to 4GB in my old iMac so thought it would be ok for now! Still, buying an extra 16Gb to take it up to 24GB total seems cheap enough!

 

Thanks tardman91, the 24GB of RAM that I now have in the iMac means that I can flick faster than I would ever realistically need to!

 

16GB from Crucial.