Descriptive Problem Summary:
While moving a direction for a while, then trying to do a command or something, its delayed for about 3/4 of a second. The delay is related to how long you've moved in a direction. Also, when you let go of the direction your moving (depending on how long you've held it) you'll keep moving in that direction for a little bit.

(Also, I'm using pixel movement [Forum_account's sidescroller library] but even so, it still happens in other games)

Numbered Steps to Reproduce Problem:
1.) Move a direction for about 5-10 seconds
2.) Preform an action/command while still holding the direction your moving
3.) You'll notice that there is about a 1/2s delay when doing the command.
4.) Move for about 10 more seconds still (you should be still holding it from step 1)
5.) Try to preform a command, this time, the delay is more substantial and noticable.
6.) Let go of the direction your moving, and you can see yourself move for a little bit even after you've let go.

Expected Results:
Timing of commands should be when you preform them

Actual Results:
Delay relating to how long you've been moving in a direction

Does the problem occur:

Every time? Or how often? Every time and any direction
In other games? Yes
In other user accounts? Yes
On other computers? Same problem on 3 computers

When does the problem NOT occur?
It doesn't occur when I don't hold a direction for too long, or atleast less than 1 second

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked?
This problem did not occur in build 489

This problem occurs in builds 490+

(Visit http://www.byond.com/download/build to download old versions for testing.)

Workarounds:
I'm not sure of any

Edit : (11-7)
It seems when I do a command slightly after I start moving, the problem doesn't occur, but ONLY slightly after, meaning not before I move, or more than slightly after moving.