Does setting an object phantom reduce lag?

I'm a grandpa in SL terms (joined Nov. 30th 2004) and I've seen and heard so many things it's nuts. Now....I recently started renting a new spot at a new nicely built mall. They sent me an IM asking me to set my vendors to phantom because it will help reduce the lag. It's something I had never heard of before. It's not a bother to me so I went and did it for them....but I'm curious as to whether or not this actually works. I'd "assume" that because the object can be passed through it is less of a toll on the physics side of things....but....any one have any ideas?

It would a bit I suppose - if something is phantom there's no need to bother calculating collisions etc - but in a whole sim full of non-phantom objects, the impact would be immensely minimal. Perhaps if they have half their prim allowance going to vendors, that would be significant.

Making a prim phantom is significant in terms of lag if it is a mega prim being used as a floor at a busy location - not that phantom floors are generally useful.

Thanks for the quick replies....I might have a few of my friends who own sims with malls do this to try and help them.

the impact isn't huge, theres much more impact on physics lag if you change an item from physical to normal(static). but anything that can be collided with or thats solid and moving can benefit by being phantom including sculpty trees and lawn ornaments, etc. but if you don't need it for a floor or a rail or a wall, sure why not, it's still clickable and still looks solid

just don't use llVomumeDetect to make items phantom and expect that'll help (since it still calculates collisions)

One place where it should make a difference is in repeatedly rezzing an object, especially if there are avatars or other physical objects in the vicinity. That might be a consideration in malls with "holo-vendors" I suppose.