That was a fact check fail for me, I thought I had 12,200 objects in my current system, but its 12 hundred. 10K objects would probably crash my computer, or most peoples computers.
At any rate, its the system that I'm trying to do an accretion on, imagined Alpha Centauri system and it has yet to hit one hour timestep with the auto bar all the way into the red, heck, it hasn't even breached 6 minutes and is usually on a couple of minutes timestep. While the amount would be mostly to blame, I'm currently combing through the objects to see if theres any close orbiting objects that are forcing the sim to slow down. Although as the objects spread out, I'll see if theres any improvement.
Edit: It's also possible that some may be orbiting each other without actually having the gravitational relationship line to each other as I've observed a few that seem to be doing a binary type orbit around each other.