Suddenly when I hold down arrow key it takes a moment for OSX to respond This is odd. 

No recent system updates. Before when I would hold down an arrow key, my cursor would immediately start moving left/right/up/down but now when I hold it down there is almost a 2 second lag before it begins to move. To clarify, the cursor DOES move one space on keypress but it takes another 2 seconds before rapidly moving in the direction I am pressing.

I should note that this happens across all apps. It is a system-wide change. 

I am running Yosemite 10.10.5
Check the System Preferences...:Keyboard, and see if "Delay Until Repeat" is set to Long. If so, set it shorter.