Urgent! FCPx incapacitated, deadline looming.

FCPX has ground to a halt very close to the end of a project, I've bought 16gb of Ram which I was planning to put into my machine after upgrading to Mavericks the RAM wont work in the 10.6.8 ox, I've read not to upgrade while in the middle of a project, yet my deadline is looming fast, any thoughts on speeding up my 4gb macbook pro rather than biting the bullet and upgrading the osx, will deleting older events and project folders help, any ideas?
Also, any ideas of the safest way to upgrade osx mid project?

I'm confused, why won't the RAM work in Snow Leopard? If you are able to run FCP X then you are using SL in 64 bit mode meaning the extra ram will help.

Adding ram mid project is A OK. Updating the OS and FCP X version mid project, not advised.

You should be OK to add the ram, if something doesn't work, you can always swap it back. FCP X needs at least 8GB to even run well at all, 16 is better.

Yes clearing out any unused Events/Projects can help free up the system. This may help with getting you back up to speed as well: fcpx.tv/troubleshooting.html

Upgrading the OS isn't that big a deal but Upgrading FCP X to the newest version is and it is not something you want to do right now unless you have to. Try the link above first.

To upgrade to 16gb RAM on my mid 2010 macbook pro(which originally could only hold 8gb) I need to upgrade my osx as well.

No, the OS has nothing to do with how much RAM your Mac will allow you to install. If the limit is 16GB RAM, that will not change with any OS upgrade. That is a hardware limitation, not a software limitation.

Not with a Mid 2010 macbook pro, 13" 7,1. To add 16gb to this 8gb limited computer you need to update osx, at least when buying the specified RAM from OWC.

The 13" 7.1 will take 16GB RAM, with 10.7.5 due to the EFI update that goes with it, etc, etc. Yes, that one model it is correct. I'm surprised you haven't upgraded the OS in all this time.