OP is making their life more difficult, and this tread can quickly devolve into a win/mac/*nix fight.
It *has* descended there already, but windows wasn't invited to the party (but showed up anyhow - sort of how they try and sell you an automatic transmission when you tell them you don't want one)
Please state what you currently have, as laptop and desktop solutions are different. Chances are an internal SSD upgrade and maybe a RAM upgrade will tide you over. State where you have your LR library. FW 800 is much faster than USB2, but more importantly FW is at a lower CPU overhead on a Mac. If you're working against an external USB2 drive, make sure there isn't a hub between the drive and your computer.
You're right; I should have explained exactly what I had an how it was set up (and explained where the slowness was, which I did later on).
Primary work is done on a pre-"i5/i7" iMac (back when intel was calling the stuff 'core'), keep forgetting to look at the specs when I'm at home. Catalog and Raw Cache file are on primary drive (most likely a 5400rpm), but the raw files are on a USB HDD, which I've pretty much decided is the real issue. I tried bumping the cache size to 10GB as adobe suggested, with some speed improvements.
Fusion drives like in the new iMac's are nice, and you can do it with any Mac running 10.8 and that has 2 drives, a SSD and a SATA drive.
I currently have en route a FireWire/SSD that I'm going to move my current set of RAW files to, and the Cache File, and Catalog. If THAT gives me an acceptable improvement, then I'll probably just get a newer machine with faster drives and USB 3.0 some time in the future.
Firewire 800 is faster than USB 2.0, but not THAT fast. You'll see a realistic read/write speed of about 60-70MB/sec over Firewire 800. Most current generation SSDs will exceed 500MB/sec read speeds. You will notice a little improvement due to the SSD having near instantaneous access times though. I wouldn't waste money on a SSD if FW800 is the only connection option. I guess you don't have Thunderbolt?I did a side-by-side file transfer on Windows and Mac with USB 2.0 vs FireWire 400 and that was NOT my experience. I don't know if USB 3.0 is less processor intensive, but 2.0 was a little more than 1/3 slower FW400 when I did testing a few years back. I could easily transfer files quickly via FireWire from my mac to PC until windows decided that the card was unrecognizable out of the blue.
No Thunderbolt on the iMac.
Windows wasn't really invited to the party, yet somehow it got in (that will probably be fixed on Patch Tuesday).
At any rate, this was why I brought up a Hackintosh (a hand-built PC with similar/same components as a mac) . . . they're still expensive to build if you use good parts.