This version work nicely in my machine .  Shadow map render seems faster though final render had little speed improvement  if you use raytrace shadow .

DAZ Studio 2.2 offer you to save file before rendering process , I suspect this trick to reduce wasted RAM , because render result immediately  was write on hard disk . Not saved in memory .

I dont know about 3rd party plugins since i dont have ( use ) it .

Something i noticed  is about display improvement . In 2.1 .... my display adapter seems couldn`t handle Open GL facility , but i dont have similiar problem in 2.2 .

Try lowering desktop resolution and see if this solution solve your open GL problems . I cant guarantee this method always work , but this work in my poor machine and display adapter

Thanks