Windowed mode unresponive

Make sure you don’t have many back ground processes running if you can and don’t worry if the mouse is sticky from time to time. If you leave it alone it generally unsticks in a few seconds.

As a general point also avoid moving in and out of the window whilst the Game is doing stuff (moving ships etc) and don’t worry if the game seems to stop during certain processes particularly saving, maximising the game window as it almost always works out ok just takes some time.

The game also runs well in full screen mode and its easy to swich in and out but dont use Alt-Tab as SEV like most games dosent like that method

As evilginger said, make sure you aren't burning system resources outside of the game, especially if you run it in windowed mode so you can have it process turns in the background.

Try defragging your harddrive, and updating drivers. These may also help your performance. Run a virusscanner and make sure you don't have any viruses or malware running in the background while you're at it, just in case.
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There are 10 types of people in the world:

Those that understand binary, and those that don't.

It's probably graphics card drivers.

Also turn off mouse pointer shadowing from the mouse screen of the control panel. That helps for some older logitech mice with this problem.