what with all the lag (spikes every few seconds or the game just dragging me around making my movement/actions erratic and useless) i've been suffering i've been looking around the forums here and far as i can tell, said lag issues are by far nothing new at all. that said, i also have another issue, see title.
i play this game from kongregate http://www.kongregate.com/games/SpiralKnights/spiral-knights (sorry if such a link isn't allowed >.>), and the games resolution is locked at 1024x768 60Hz. any attempt to change that to a higher resolution or fullscreen mode (my laptops max resolution is 1355x768) simply makes the game close out automatically and upon re-launching the game all changes are reverted back to said locked settings. i saw in 1 thread (old from january 2012 so may not apply anymore) that switching to full screen may help with lag bug for me thats impossible.
oh and said lag isn't frame rate related as otherwise my laptop runs fine, same with my internet connection as i can browse and load other things just fine with this game running despite the somewhat hefty cpu/memory load it puts on this computer. a 1-2 bar connection never lags in certain other java games >.> so i dunno why this one is so bad about it.
Your laptop resolution is unusual, that I can confirm. Maybe that's why you can't switch to fullscreen. Try to set a defined resolution for your window, then play fullscreen?