Try to click Settings > Networks and fast click on More,and quick Back button,try doing the same thing but click Display and More and you'll see the difference.
This short of lag isn't present on v20c.
The second thing is the heat,wich is more present on v20e.
The cooling is more quick on v20c.
About mmc code error it didin't happend to me never! And i flashed v20a,b,c,d, and now v20e-Orange , all euro. My phone is a H815 EU.
I think in the end i will get back with v20c until LG release 6.0.1.
Please take in consideration that this is just my opinion and experience so far.