SK has been working brilliantly since I got a new computer but in the last few days I have played some of the special event levels for the first time and experienced severe stuttering/frame drops. It happened on Shadow Lair Firestorm Citadel 2 days ago and now it has happened twice on The Grasping Plateau level of Shroud of the Apocrea prestige mission - it only seems to start when I reach the level for the second time in the same run. The stuttering makes the game completely unplayable and only a restart fixes it.
Running windowed mode @ 1600x900 60Hz
Windows 8.1
Java 1.8 Update 31 (32bit)
Display 1680x1050, 60Hz
Intel Core i7-5820K CPU @ 3.30GHz
Graphics: GeForce GTX 970 4GB, Latest video driver.
RAM: 32 GB
ports 47624-47634 forwarded
It's a known bug, the Apocrea mission leaks memory and you'll have to restart every other run or so.
Since you have a lot of ram you might want to use 64 bit Java and increase the amount of memory SK uses to 4GB (see this thread), it'll still start freezing eventually but it'll take longer to do so.