[Sholander]

already now 1080P with high bitrate movies having a 4 core CPU fails to do the job well in scenes with high peaks of bitrate...

Interesting thing about this on Amlogic boxes. Your addon works with old and new widevine versions (libwidevinecdm.so.4.10.1303.0 and libwidevinecdm.so.4.10.1440.18)
Using old (4.10.1303.0) version plays 1080p high bitrate streams up to 25Mbit/s without problem, and using new (4.10.1440.18) version it begins to skip frames with bitrates higher that 7-8Mbit/s. Also NF addon is the only one, using inputstream.adaptive that I know of, that works with old and new widevine module versions.
All above tested on Amlogic boxes running CoreElec 9.2.0/Kodi 18.4, 1080p on S922X and 720p on S912/S905X