NBT Studio lags heavily when opening ClassicWorld files

[mudkipdev]

It's just an NBT format, so there's no reason why it should be lagging. Sample .cw file is attached. (remove .txt file extension, it's to bypass GitHub's file extension limits.)

custom.cw.txt

[Solitudocultor]

Probably applied to the NBTs saved by the ClassiCube client. The same thing happens with schematics.

Upd. This is most likely due to large byte arrays. The same thing happens with vanilla Minecraft Indev levels.

[mudkipdev]

Also hangs on Indev .mclevel files (you have to open the "Map" compound, at which point the huge 256x64x256 byte arrays are loaded and NBT Studio hangs).

sample.mclevel.txt