"W" key causing lag

[Evilbookworm]

Sorry to bother you, but I haven't found any sort of help online for this. I love the game, but every time I hit the "w" key (rather important) the game sticks for about a second or two. not gamebreaking, but rather annoying. If I reset the forward key, this doesn't happen, so it's the key itself. Is there a fix for this?