Memory Management

I have a small project, some instruments tracks with 3 vst synth and few audio, about 20 tracks.
I do nothing, just opened the project. About 3 GB Ram are used when project start…Consumption of physical memory just growing minute by minute. Still do nothing. I have disabled auto save function and back-ups. After 1 hour, all my 16 GB ram memory is full and Cubase stop responding. Need to restart.
Every one with same problem ?

Cubase 9 PRO, win7-64 pro, Intel I5-4460, 16GB Ram. 2TB HDD.