Operating system: Win10
Graphics card:RTX 2080ti
2.8.45 -> "blender-2.80.0-git.1af810b4ff17-windows64"
Short description of error
instances geometry dont share the same geometry data when rendering, they act like shift d geometry in terms of vram.
10 instances of an object is 10x times the ammount of vram that the geometry of one instances take.
blender 2.8 right now is unusable with large scene that have large ammount of high poly instances. I think its quite a big deal.
Exact steps for others to reproduce the error
step 1: create a scene with only a suzanne set to 5 subdiv subsurf modifier, applied it and a camera + lamp.
step 2: render suzanne is 117Mo for me
step 3: alt d suzanne five times and do a render. its not 117Mo but 579Mo, x5 the ammount of vram, so the instances are not working correctly.