Hi Prashant,
I discovered that big projects are challenging for FCP which is not too graceful as it runs out of memory.
First of all make sure that there is nothing in your project that is not absolutely necessary. Don’t dump every last thing in there willy-nilly. For example if you have a folder full of temp music do not create a bin in your project and put it all in there – that will use up a lot of vital memory that you could be using for your sequences. Get the music directly from the finder or use iTunes if you need a way to index it. In fact anything you can access directly from the finder and can live without having in a bin should be handled that way.
If you have multiple backup versions of your main sequence or old roughcuts, assembly edits etc., store them in a separate project,delete them from your main project and only open that project if you need to access those sequences.. then close it.
Do not work with multiple sequences open unnecessarily. If you are not using something close it.
More extreme – If you have a ton of rushes you can try keeping all your bins of raw scenes in another project from your main project. Open that project and copy the bin for the scene you are working on, then close the storage project. Delete the bin when you are done working on the scene.
You can put as much memory in your computer as you wish but FCP only accesses a limited amount of it. I think it’s four gigs? So if you are working on a very large project you must really become strict about what you put in your working project and anything you don’t absolutely need should be removed.
Anyhow we had similar problems and that is how I solved them…
Good luck.
jason