x265 aka HEVC
 

this is a new video codec.
it's really good - the normal tv episode that has been encoded to 350mb with h264, now 150mb with x265, and it looks better. wow.

but it's very resource hungry.

my old 2-core desktop can't keep up with it.

question:
is it possible to tweak media player settings to take some load off the cpu's, either by sacrificing image quality or by making better use of hardware accel or both?
fwiw, i have an nvidia geforce gt 610 with nvidia proprietary driver.
i use mostly mpv, but other suggestions are welcome, if it has the desired effect.
my mpv.conf currently looks like this and i admit that the man pages confuse me.

ps:
all other codecs work just fine, even with 1080p

There is no hardware decoding of x265 with your graphics card. You need a card that supports vdpau feature set F, very few cards out there can do that.