OK, so we've gone through several discernible stages here:
Thread title: "Stardock Spyware is slowing down my computer"
Now, I'm no expert in how to interpret English sentences (oh, wait, I am), but this would seem to imply that the program in question may fairly be categorized as "spyware."
Second post: indicates that, unless you buy the retail version of the game, you can't install patches without also installing stardock's "sneaky little program," again identified as "spyware."
So far, so admirably consistent. Now the potential for confusion erupts...
Tenth post: "It could be spyware, or it could be something stardock thinks they need to provide better service. Who knows? I am not going to assume it's evil..."
Then, the sixteenth post: "It doens't matter if you call it spyware or not, just make sure you get rid of it."
Ah, but it does matter if it's spyware or not. Even the most "hardcore" gamer would be more complacent about a program that caused a performance hit than he would be about a performance-damaging program that also reported his private data without his consent -- i.e., "spyware." "Spyware" is simply the wrong term for an innocuous program. If this is difficult to grasp, imagine this scene:
Doctor: "You have cancer."
Patient: "WHAT?!"
Doctor: "Well, technically, it's a hangnail. It doesn't matter whether you call it 'cancer' or not, it'll hurt and you should get it fixed."
Finally, I'll note that you can still patch GCII, with the downloaded copy, without risking any background processes that might impact your FPS. If you click the "Downloads" section of this website, you will be taken to a page that has, inter alia, a link to the latest patch for GCII. You don't need to go through Stardock Central and risk background processes. Or, Barthon noted, Stardock Central actually has the option of turning it off. So everybody wins.
EDIT: I need to learn to type faster.