I must live in a sheltered world. Is this the file size when loaded into PS? If it is the size after a few edits then cropping at the beginning of the process ( recommended ) would mean a smaller file size further into processing?
I would not be able to comment on the first part, you could very well be
(sorry jokes apart) <if you really insist on putting yourself out there for comments!>
but for people who work with multi-layered files, or high pixel dimentions.
A 4.5GB isn't that hard to achive, you can do your own math, as to how, i have flat files that are 10-14GB in size, which are from stitched panos, some of these were a struggle when i had less ram. You will get there if you work in 16-bit and more so if its in 32-bit. Obviously as you work on a file and start adding layers upon layers the file size will slowly crawl up, if the file size stays at that size when saving depends how you save your file and if you save with compression etc....
But don't let it shake your world, I do have 96gb of ram in the machine now, so its made to handle the load :-) I am about to give CS6 beta a trial run... i'll report back later
I am sure this is all deviating a bit from the actual topic - one persons issue was that he is experiencing crashes, and it happend to be while working on a 4.5GB file, now if we could get more info on that matter, by perhaps look at the memory dump file. Can the error be replicated?
All the best and sorry for the rant
Henrik