I'm using Windows 10. I recently got two monitors for my desktop. When I drag my mouse or a window to the other side there seems to be a sort of lag before going to the other monitor. What I mean is when I drag a window to the other side it doesn't split the window in half on one screen and half in the other screen. The window just cuts on one side to another. When I drag my mouse from left to right, it doesn't go to the other side of the monitor immediately. This is hurting my wrist as I have to move my mouse farther to one side than the other.
While I can't say for sure, that might be caused by using 2 different graphic cards (like built-in one and PCIe GPU). If using the same card, you might want to explore modes like "surround" on NVidia, or their equivalent for other manufacturer ("spanning" might be the term for Intel), which will make your 2 screens appear as one to Windows. It however has consequences like spanning the taskbar over two windows, and potentially maximizing windows to your 2 screens as one.
The answer given by user1532080 is a good possibility, but doesn't cover another possibility: Windows Snap.
As referenced in my comment to which you did not respond, Windows offers a application window management feature called Snap in recent versions of Windows. The primary interface clue for this feature is a slight hesitation or "bump" as you drag application windows between screens. This bump happens as the mouse cursor crosses over from one screen to the other.
Moving your mouse more slowly, Windows assumes you're likely to be trying to utilize this feature, and so the bump is more pronounced, making it easier to stop at the right point and snap the program to the desired area.
Moving your mouse more quickly Windows assumes you're likely just trying to get the program to the other screen, and the bump is less pronounced or even entirely invisible.
If you do not wish to use the Snap function, open your Start Menu and type "multitasking" to find the Multitasking settings window (in Settings, it's under System > Multitasking).
You can turn off the features you wish here. All of the Snap functions are at the top of the Multitasking window in Windows 10 build 1809.
I solved this with the display setting in all of my Office programs at the bottom of the screen right before the window ends and turns into the taskbar. I think it is the same problem. When I move a window to a new monitor it would get caught like it was asking me if I wanted to snap the window even though I was moving the window very quickly.
I am having the problem with the File Explorer and can't seem to find a solution.
I used the option to optimize for compatibility, not best appearance. Office Display Setting Screenshot