Rolling lag spikes since last update

I've been tinkering with the graphics settings for some time, and finally have to admit defeat and ask for some help, here.... The past couple of days, I've been getting severe reductions in FPS on a regular basis, every five to ten seconds (it seems to depend on how big and complex the map is, so it might be ten seconds in sector space but five seconds in Starfleet Academy.)

Basically, everything will run nice and smoothly for a little while, and then WHAM! … I... am... moving... very... slowly... and... buttons... do... not... respond... and... then it speeds up again and runs perfectly fine until the next lag spike.

I've got a screen cap with the FPSGraph running so you can see the lag spikes in the Academy - and also my graphics settings, though I've tinkered with most of them and not got any significant change.

Here's the picture.


Any ideas? Because, as things stand, I'm finding the game pretty much unplayable, what with being trapped in treacle every few seconds.