Added debug screen screenprint (processor speed, java version, some chunk info, FPS, etc). Lag issue is very pronounced in this area. Perhaps the initial chunk conversion had a glitch? subsequent chunk loading seems to be ok- the sun and animals don't lag when other, more distant chunks were loaded into the game (i.e. the nether, more distant Overworld chunks).
Attached log file. If you need me to perform specific steps and then provide fresh system files, please let me know.
With Java version 1.8.0_181-b13, the backup feature now seems to be working. This issue can be resolved/closed.