'Out Of Memory' issue and over large Project File...

Hi everyone, my issue is a common one but yet to find out reasons why after trying many suggestions.

I am working in Final Cut Pro 6 on an edit 35 minutes long. It's a holiday video edit of a snowboarding trip filmed on GoPro HD and a small handy Sony Handycam. All rushes are transcoded to ProRess 422. I have cut the edit and doing the final touches with the colour using Synthetic Appertures Color Finesse 3. My project file starts off at a mere 17MB before colour grading/correction from what I can tell seems pretty normal. By the time I get to around half way my Project ile has increased greatly to over 70MB, FCP becomes slow and unstable then I start to get crashes and reloads of the project take around 15 minutes or more to open. This seems quite a jump to me once grading starts?

Originally I did have around 6 sequences of footage (one for each day of shooting on holiday) where each contained all the usable clips I could possibly use for the edit. Then a Master sequence where I would paste my desired clips to for trimming and editing to music. (all music in AIFF)

I have deleted all folders in the browser that arent in use now and the only sequence I have now is the master, nothing else at all! No Motion graphics but some text at the start of the edit, nothing animated. No stills, but I do have some freeze frames but I'd say no maore than 20 over the whole 35 minutes. I have deleted unused render files and trashed preferences.

I did see somewhere that someone suggested splitting the edit in to two different projects? There wasnt a clear explanation of this.

I'm running....

iMac 24 inch - early 2009

2.66 GHz Intel Core 2 Duo

8GB 1067 DDR3

NVIDIA GeForce 9400 256 MB

OS X10.8.2

Hope this is all you need to help me get this edit completed and exported off. Any more info you need just ask!

Thanks in advance.

GK