I have been getting huge lag spikes lately as well, I did a test to see if it was my ISP, no problems there, I was getting my full 25Mbs/10Mbs with ping of 6ms.
I found out my server ip while in game by typing /ip , then did a tracert to it.
From what I see it looks like there is a problem with a router that is giving uplink service through Level3 Communications, as can be see by my tracert to the North American server I am connected to at IP address 64.25.33.79:
9 7 ms 8 ms 7 ms ae55.bar2.Toronto1.Level3.net [4.28.138.45]
10 * * * Request timed out.
11 40 ms 40 ms 41 ms 4.59.197.34
12 40 ms 40 ms 40 ms 64.25.32-9.ncsoft.com [64.25.32.9]
13 42 ms 40 ms 40 ms 64.25.32-26.ncsoft.com [64.25.32.26]
14 42 ms 61 ms 41 ms 64.25.32-82.ncsoft.com [64.25.32.82]
15 40 ms 41 ms 40 ms 64.25.33-79.ncsoft.com [64.25.33.79]
As with any server/client communications, when you do not get a response in the time the client expects, all goes to heck in a hand basket…lag spikes, disconnects and all the totally not fun stuff, when you just want to go in and bust a few heads for a while.
They need to talk to Level 3 Communications and tell them to get the router fixed.