Whether or not it's slightly faster or slower, you don't worry about speeds for cycling through data when you have much more intensive processes like collision and rendering. I don't know if this gains or loses 2 milliseconds, but it's not really going to make any difference. I'm guessing it would be slightly faster than cycling through all your types looking for the right entity.
Check out the thread called "Add a free four-byte slot..." for info on getting and setting entity properties.
Check out the thread called "Add a free four-byte slot..." for info on getting and setting entity properties.