Game freezes a couple of seconds when changing mipmap level parameter

Mipmaps can take a while to recalculate when adjusting the Mipmap Levels slider in the video settings. Because they are recalculated as soon as you move the slider to a new position, the user interface becomes unresponsive, making it very difficult to set them to a specific level. On slower computers, the slider will sometimes jump back to the previous setting, or another setting entirely, because the mouse detection becomes erratic due to the lag.

Suggested solution:
Recalculate the mipmaps once the user releases the mouse button, rather than when they click on or drag the slider.