Is anyone else getting abysmally low frmearate/slowness when they load a game?

I could play SoaSE Trinity on max settings with max players with huge fleets duking it out and no performence loss.

When I purchased Rebellion it was pretty much the same, i played a massive game with max players on max settings and with huge battles and everything was still running silky smooth.

However, I loaded the same game this afternoon and the game was permanently sluggish and suffering from a monstrously low framerate issue. I tried turning down all the graphics and it was exactly as sluggish.

I decided to start a new game with the graphics amped up again to check if it was the game, and the new game was running at proper speed/framerate.

Does Rebellion just have issues loading large games?

And I dont think posting my specs should be neccesary, the fact remains the computer can and was handling it perfectly up until loading that game.