Framerate still an issue in Spiral Knights.

I'm using a Radeon HD 5570 on my computer currently. This card is capable of running most games I play just fine. I can run Left 4 dead 1 and 2, Mass Effect 2, Battlefield 3, etc, all on maximum settings and the framerate stay in a very playable range of 25-48. But this game I'm lucky to get 15 frames in some areas, even with low settings and compatibility mode turned on.
What gives? Why is this game so difficult to run when other higher-graphic games work just fine on my card? What can I do to fix it and make this game run smoothly?

California. And my internet connection it's just fine. Framerate is the issue, not latency.

Turn off vertical sync.. I noticed an insane increase in frame rate when I did.

Disabled Verticle Sync and Catalyst A.I. No improvement at all.

There's some things you can try.. let me tick off the list:
- Open your video card settings, turn the defaults down, v-sync might be forced on regardless, so disable it there.
- Reduce AntiAliasing settings.
- Since Spiral Knights runs on Java, see if updating java helps- I believe it uses java within it's own game folder.
... other than that I'm not so sure. Sorry!

AMD Athlon X2 processor, 2.9ghz speed. 5GB of DDR3 RAM. 500GB hard drive.
This is my card: http://www.newegg.com/Product/Product.aspx?Item=N82E16814102874

Athlons are pretty dated, but I doubt that's the issue especially at that speed. I personally play on a Core2Duo at 2.53. You've stated you're not having issues with your other games so I assume it's not an overheating issue(couldn't hurt to clean anyways though). Java could be the issue despite having updated, I know for me at least java tends to eat a lot of my CPU power. What else to cover....if you've not defraged or cleaned your registry in a while I'd suggest doing so, you'd be surprised how much of a difference it makes. This really is a conundrum afaik, it's not making much sense to be running at those framerates.

I don't know exactly how to properly update Java in the SK folder.

Well the location would depend on if you downloaded through Steam or not. But before I forget I again, are you running the latest drivers for your graphics card? Also, it's my understanding that the order in which things are applied make a difference. By which I mean one would need to uninstall SK then update java/graphics drivers, then re-install SK. I'm kinda shooting in the dark atm.

Java is separate unless your using Steam (its a little complicated).
Java downloads
http://java.com/en/download/manual.jsp

Ok.... then update java.
Then:
1. Go to C:\Program Files (x86)\Java\jre6\
2. Copy everything in there
3. Paste to C:\Program Files (x86)\Steam\steamapps\common\spiral knights\java_vm\

Alright, did it. No improvement at all.
I'm out of ideas. I just don't know what else I can do that might work. Why the hell can my card handle games like Dead Space 2 and Mass Effect 2, but not this little game?

I had seen advice from an Admin here on the forums, can't remember who now. But they said if you want to risk your game possibly needing to be reinstalled, you can make a new text file in your Spiral Knights folder called 'extra.txt'. Then put this code in there: -Xmx512M (or if you have a lot of RAM, -Xmx1G)
I use it, and it makes loading screens take a little longer, but removed most client based lag i get.
Where do you live? It may be the servers.