[sow07]

What workaround? And what chromebox?

There seems to be a kernel bug in 4.19 that affects Haswell chromboxes particularly hard. The work around is to edit /flash/syslinux.cfg as assuggested below. If you are really interested, the whole tale of woe played out over pages 315 to 320 or so in this thread.

 ssh root@<ip address>
<enter password, default is 'libreelec'>
mount -o remount,rw /dev/sda1 /flash
nano /flash/syslinux.cfg
<add ' pci=nomsi' after 'quiet'>
<save and quit: CTRL+O CTRL+X>
reboot  

I have a 11/2016 vintage installation of the Mr. Chromebox on an Asus Chromebox CN60 which doesn't have syslinux.cfg.  Mine uses extlinux.conf.  Nevertheless, the workaround solved my issue which was indeed painful (1.5MB/s network performance within Kodi vs. 60MB/s).

Note, I was able to get between 20-30MB/s using SFTP both before and after making this change.  Not sure why it wasn't impacting SFTP but the file manager within Kodi was virtually dead in the water.