I chose lowest shadow size and 1024 sized textures, and still only around 500mb away from OOM
That's not of course a problem caused by CYVR, which doesn't take so much more memory than any other scenery, your high memory consumption is caused by the COMBINATION of everything you have installed, with the main offender being a memory hungry airplane, and then the rest of the scenery you have in the area, the AI, etc.
This has been discussed so many times on the forum: CYVR is not particularly heavy on VAS, not much more than KLAX, but it stays in an area that is already very heavy on memory usage, even by default, and there are several 3rd party add-on products available AND the most memory hungry products out there, are finally available for P3D...
Have you checked the DIFFERENCE in free memory, if you use a default airplane instead, with everything else being the same ? That will give you a clear indication about what's really stealing your VAS.