Similar to Ubuntu Microsoft has decided to add a bit of resistance on the edges of a multi-monitor display setup. This allows the system to popup a menu (like the charm bar) before allowing your cursor to move to the next screen.
Please backup before doing any of this!
Go to the registry. You can do this by typing in regedit in the start menu search.
Navigate to HKEY_CURRENT_USER\Control Panel\Desktop\
Change MouseMonitorEscapeSpeed to 1 to disable (0 to enable).
Change MouseCornerClipLength to 0 (default is 6).
It will then require a restart for the changes to take effect.
Sticky Edges for Multi-Monitors – Enable or Disable
How to disable sticky corners in Windows 8?