We recently were able to do some server profiling of the Powers system, and Inspiration was revealed as the far-and-away leader of the pack in terms of performance impact.
But it was, by no means, alone.
We're also having to clean up many other powers that in years-gone-by probably would not have been an issue. But as the game has matured, and players gain more and more access to different sources of additional powers (Rep Traits, Specs, Starship Traits, increased # of equipment slots, etc, etc.) it has really started to add up.
In fact, we're going so far as asking our poor, overworked programmers (like /u/CrypticBatsoup) to create entirely new code paths so that we can lighten the load of certain types of powers on the back end, without having to re-design their functionality.
Long story short: Inspiration changes should improve matters significantly, but it's not the end of the road. And we're going to continue improving things for many months and years to come.
Also, Attack Pattern Beta was apparently the #2 culprit, as I understand it. So... consider laying off the Recluse spam?