Certainly for large maps, and while I haven't tested it, I doubt it is any better on smaller maps.
I finally completed an Immense map game where I was determined to win by influence. I finally won the game at T 410. That alone is not the problem.
Did I enjoy the game or get any satisfaction out of winning? Hell no.
Playing on normal, the game was all but won by T 175-200 when I was up in power 5X over the closest of 7 AI. By the winning turn I was at 50,000 + power vs 2000 over the closest AI. I was earning over 40,000 BC per turn and I had researched every tech. And, since before T 200 I had been using every trick in the book to build influence.
When the game is that much out of hand and your influence is insufficient to have won a long time ago, Influence is no longer a valid victory option. It is just a dreary and tedious clickfest for turn after turn
I know that Influence victory is not popular with a lot of players, but this is ridiculous. The game could have been won by conquest a hundred or more turns earlier so there is no way that Influence was hindering a conquest victory. The lost defenders my surveyors were finding could defeat most of the AI fleets. There hasn't been any discussion on this lately and as a player who enjoys winning by Influence, I am thoroughly pissed off that this ridiculous imbalance is apparently being ignored by the devs.
If Influence Victory is not important enough to make it a valid option stop advertising that it is an option at all.
There are late game techs that provide a coup de gras for a tech victory. Maybe, if nothing else, there should be something similar for Influence, but I would much prefer a fair balancing to allow a quicker Influence take over when the game is at the point described above.
BTW, after T 300 or so, the game becomes very fragile and will easily crash and require a restart if you are not very deliberate in what and when you click on various commands. No slowness or jerky movement, just fragile.