So, my ping is really bad.
Or something's really bad, and it has been all week. When I go to attack, my guy kind of indecisively jerks his sword around. Crystals take three or four button presses/animation cycles to actually pick up. I slide halfway across the room and directly onto spikes. For a game like this, that's unplayable.
I'm totally willing to blame Comcast, but is there an IP I should run a traceroute to to try to see where the problem is?
(oh hey, another Aussie!)
In the last week I've actually noticed improved performance -there are no longer random lag spikes that seem to affect everyone. Level load times seem a tiny bit slower, but that's it.
I haven't heard any of the people I've played with complaining of lag for a while now.
I haven't seen anyone else complain about it, so I'm sure it's on my end. With a traceroute log, Comcast would be less likely to shrug me off, though.

As you note, we did fix the recurring "lag storm" issue, where updates from the server would slow down dramatically for several seconds every 45 minutes or so. Of course, improving network performance (and graphical performance, etc.) is an ongoing process.
The game servers run on Amazon EC2's data center in Virginia. You can try tracing a path to game1.spiralknights.com (184.73.192.155).
Well, it comes and goes, but I think we can be fairly certain it's not a Spiral Knights problem.
1 14 ms 2 ms 1 ms 192.168.1.1
2 171 ms 348 ms 146 ms c-24-6-136-1.hsd1.ca.comcast.net [24.6.136.1]
3 24 ms 114 ms 60 ms te-4-4-ur09.sanjose.ca.sfba.comcast.net [68.85.1
90.193]
4 226 ms 20 ms 91 ms te-0-10-0-6-ar01.sfsutro.ca.sfba.comcast.net [68
.85.155.34]
5 270 ms 85 ms 35 ms pos-1-7-0-0-cr01.sanjose.ca.ibone.comcast.net [6
8.86.90.153]
6 40 ms 124 ms 71 ms xe-11-0-0.edge1.SanJose1.Level3.net [4.79.43.137
]
7 248 ms 102 ms 59 ms vlan89.csw3.SanJose1.Level3.net [4.68.18.190]
8 122 ms 198 ms 22 ms ae-84-84.ebr4.SanJose1.Level3.net [4.69.134.249]
9 161 ms 173 ms 133 ms ae-2-2.ebr2.NewYork1.Level3.net [4.69.135.186]
10 481 ms 502 ms 171 ms ae-6-6.ebr2.NewYork2.Level3.net [4.69.141.22]
11 130 ms 133 ms 175 ms ae-1-100.ebr1.NewYork2.Level3.net [4.69.135.253]
12 844 ms 212 ms 204 ms ae-3-3.ebr2.Washington1.Level3.net [4.69.132.89]
13 380 ms 199 ms 182 ms ae-82-82.csw3.Washington1.Level3.net [4.69.134.1
54]
14 192 ms 193 ms 450 ms ae-3-89.edge1.Washington1.Level3.net [4.68.17.14
4]
15 * * * Request timed out.
It's Comcast, I live in Australia and my ping is nowhere near that bad.