Best setup for cache location?

Hi all, I'm wondering if moving my cache will speed up my editing workflow and timeline playback at all. Here's what I have going on right now:

I'm editing with FCPX 10.1 on a late 2013 iMac, i7 processor, 16GB RAM, 256GB SSD, 4GB Nvidia GPU. My footage is on an external 2TB via USB 3 (720p .MOV files, about 900GB for this project). Right now, it's a 5400rpm drive, but it will eventually be swapped out for a 7200rpm. I don't own my footage drives, they get traded out between me and my boss on a per-project basis so I can edit for him from home. At the moment, my cache is located on my internal SSD boot drive along with my applications and project files of "Libraries". I am also aware that maxing out my RAM to 32GB is the easiest way to boost performance, but at the moment that is a fiscally difficult upgrade until later this year.

Here's my question: I have a spare 250GB SSD sitting on my desk in need of an external enclosure. I am thinking about purchasing a USB 3 enclosure for it, and keeping my cache there, separate from everything else. Will this give me a noticeable boost in speed?

Thanks!