3000 high rez - then vary depending on tree size. Sapling should be low poly. Big tree more polys.
0-300 lowest rez
problem is that the lodding for the vegetation system is not yet fully implemented and won't work for you atm.
so a mid size tree will do the trick.
With the vegetation system, after a certain distance, they turn into impostor billboards which is why the performance keeps up.
But at certain angles, they can look bad. All to improve lol
palm tree is around 400 polys
spruce 2 is around 3000 polys