I have two different intel based boxes (Libreelec Generic x86_64 with Intel hardware) giving me the same issue (to different degrees) when using the netflix addon and only the netflix addon.
As the logs will show a "large audio sync error" then the stream pauses then when its ready it will go fast motion to speed up to where it should have been. Once this starts though it seems to get worse so I can often watch for almost an hour before seeing this but when viewing a second hour these pauses would become more and more frequent
I do see that this Netfilix addon is using inputstream adaptive, with either VP9 or H264 and I can switch it between h264 and vp9 (in settings) with similar results on either.
I have ruled out Wifi as I have tested on 2.4Ghz and 5Ghz as well as wired ethernet. Also the unit remains connected to the network and able to serve up Samba shares and SSH connections when this happens. Internet and network functions all seem normal even when this is happening.
The problem is worse on my Asus Chromebox CN60 (via MrChromebox) than on the Mission One Mini PC but seems to happen on both.
One of my other suspicions was heat related that after an hour of software decoding something heats up but Kodi shows CPU heating up to about 117F when software decoding (vs 115F or so when hardware decoding) . I also used an hddtemp commmand and found the hard disk (an SSD) to be at about 115F when viewing netflix. I do believe these temps to be okay but could be wrong there.
I have tried multiple settings in nextflix and posted the problem to GitHub on the netflix addon page.
I thought maybe someone here had this issue before too.
I was thinking I have seen settings for where some temp files are written and I may try a thumb drive for temp files
Any suggestions form anyone?