In battle some ships leave contrails when they move. Is this a bug or a feature? The more contrails there are on the screen, the slower the game becomes. To the point that just scrolling the screen takes tens of seconds rendering the battle mode unplayable.

Is there any way to switch contrails off?

Gentoo Linux, AMD64, 3GHz processor, screen resolution 1920x1080. Speed is the only issue with the game so far.

Update: found it. "Graphics" tab in "Settings" dialog, "Disable Contrails" checkbox.