Starcraft – Does creep spread speed depends from amount/concentration of creep tumors

Just the Tumors. They act like any other building (though are invisible once built) and provide vision like any other building.

You cannot own creep so it belongs to noone and thus its impossible to know who it would provide vision to (imagine a ZvZ).

I did some testing and found that about 5 is nearly optimal. You have to wait about 1 second for the creep to reach its maximum spread, which seems ok considering you have to macro other stuff.

With 6 there is no waiting, but I think 6 is too much.

Further information:

TLO hotkeys his active creep tumors so he can hit the perfect timing consistently. He also plays a Zerg style that relies on 4 queens. You might want to watch some of his replays.