Ok, I think I can report now

While disabling it did help some (no freezes when playing solo), once I partied up the problem came back.

I kept the experimental "conserve one thread for system", lowered all graphics settings, set fps limit, disabled hardware rendering in Steam and I could play whole session in one launch.

When I was getting the freezes, I did not observe some temp going too high in Mango HUD but it seems it might have been some thermal spiking. For these specs the settings should be lowered for playing in a party and disabling steam overlay and steam hardware rendering can help squeeze more out of the hardware