Graphics driver hasn't been updated for 5 months. I generally don't update my graphics driver unless I experience problems with newer games or updates to games.
Was just mentioning it because if you've got windows 10 (which I don't know if you do), it might "helpfully" update them without letting you know.
I also wanted to point out that while in game, the status on the top right is showing 0-1% idle, and 30-40fps mostly (worse in battles, and the time scaling slows down if there's more than 10+ ships in the battle).
Oh! That's pretty useful info, yeah. This sounds like it's basically not using the graphics card at all and doing rendering in software. One thing that's possible - do you have two graphics cards on your computer? Oftentimes there'll be a weaker integrated card on the motherboard and a dedicated graphics card.
If the game all of a sudden got switched over to using the weaker integrated card, the symptoms would be basically exactly what you're describing. And that's happened before, that is, I've had reports of the game running fine on the dedicated card and then the OS at some point just randomly deciding to run it on the other one. The fix would be to force it to run on the dedicated card, with the specific steps depending on the card you've got (and that, honestly, I'm not too familiar with).
(Also, just as a point of interest, do you have ATI or NVIDIA? Performance on ATI is generally speaking... not great. But since it *was* good at a certain point, I'm assuming NVIDIA. So, probably an irrelevant question.)
Another possibility is that if you *do* have an ATI card, the game might have switched to *that* from the integrated card, on which it would've been getting better performance, if i.e. it was a decent Intel graphics card. That'd also explain why you're seeing more free memory, possibly.