I lasted quite a bit at first, I got a few colonies. I played with rare stars, occasional planets. So I was on par with the A.I at first because I simply bought 3 colony ships. And there was not much more room to expand.
But after that. Oh my, the A.I is like a locomotive that just keeps accelerating in speed. Before long he had all the resources, I saw fleets and fleets and fleets of fighters, so many I wondered how on earth he managed to crank out so many constructors and fighters. Felt like he must have build a fleet every turn or so, and still manage to keep his economy going, his research going.
After seeing that I gave up. Quit the game, restartet with cheat mode. And decided for fun to try one more time, except with infinite cash, only that.
After a dozen turns or so I gave up again, even with infinite cash it's tough. Me setting the sliders accordingly to someome with infinite cash, planets tailored to someone with infinite cash, amazing the A.I somehow managed to keep up well

. Anyway I don't see how you can by playing fair. And I think at these levels the A.I does a fair bit of cheating itself
p.s. A small note, I always play with all victory conditions off, so that means everyone needs to be obliterated

.