i try on 2.79 and last release of 2.8 are you shure? . is it my pc ???
could you test it please it take 2min??? do a render with a suzanne and a subsurf-modifier set to 5 iteration, 500 000 faces. and apply it. see how many vram (i got 117mo)
then alt-d suzanne 10 times and see the vram result (i got 1150mo)