The iWatch is 200+ tris so takes a long time to load anyways. WebGL/3D is around where mobile 3d is, safe range is up to 140-160k but for older really under 100k total per frame is needed to perform/load reasonably well. For mobile if you can stay below 60-80k you don't have mesh loading issues.

Hint to artists, low poly is in and will be for a long time again due to web and mobile games. 2k for a game character is fat, 1k is usable for many enemies to be drawn at once per frame. Show off your skills but also show off for the markets you target, gaming is still low poly in web + mobile.