It's important to have a playable game.
I'm on a laptop with an Intel HD graphics card, so that limits me to about 30-40k bricks ghosted at once without any frame rate issues.
If you're making something that needs players to move without this lag, then you'll need to "optimize" your build.
Inversely if you're making something like an RPG where there's no real pressure to move quickly, go all out.
Okay, don't go all out unless you're making something for show, like something that taking pictures of would be nice.
Here's a few brute examples.
15-35k (bricks) - Suitable for fast action, DM's, Challenges, Sometimes City RPG's.
35-100k - Good for leisurely RPG's, usually if your brickcount is this high, it's good to use a few strategies to break up how much a player sees at once.
100-250k - Unplayable for many low-end computer users. Take pictures of these.
Essentially you're choosing what kind of crowd to appeal to. The vast number of low-end computer users, or the fewer but possibly more knowledgeable high-end computer users. (This statement is not supported by fact, only by my own estimation. It seems that the more serious users are active on the forum to give up statistics, showing perhaps a false statistic of good/bad computers ratio.)
In the end, it's up to you to make the best out of the bricks you use. Just keep in mind the limitations of some player's systems.
Poll