freeze when moving

[Teambo100]

Yo, TOME-ies, ive got a bug that occurs when i move my character. Whenever i press a movement key the game sort of freezes and has a massive drop in framerate. this occurs ever time i move a tile and can cause massive slowdown whenever i try to move more than 1 square at a time. My computers specs are as follows:
Processor: AMD a6-3400m 1.4-2.3 ghz quadcore
Ram: 6gb DDR3 1333
Hard Drive: 500 gb 5400rpm
Graphics: AMD Radeon HD 6520g
Windows 7 64 bit

i don't think its because my computer is not powerful enough, but any input would be great!
I really like this game and this is kind of ruining it for me right now. i don't wanna go back to angband :d
thanks