Probably not related, but I had to post anyhow. When you look at your server and you aren’t even doing anything, is the CPU sitting at like 30-40% usage?
I had this in upgraded 10.1.500.12 environment. I narrowed it down to only happening while the Task Agent Service was running, but the system monitor claimed nothing was running (I even deleted all my scheduled tasks from saytem agent). I turned on Server Trace/Logging on the app server, and saw this exception being thrown over and over, quickly filling up log files:
<Op Utc="2017-02-15T20:57:33.0795118Z" act="Ice:Lib:RunTask/RunTaskSvcContract/RunSystemTasks" dur="1.0687" cli="fe80::84fc:9621:aaf:db56%12:53886" usr="NT01NL\EpicorAdmin" machine="SVICEERP03" pid="2600" tid="44">
<Exception><![CDATA[
Unit of measure is not active for Class:Other UOM:FT (BusinessObjectException)
... etc etc...
Although I’m still not 100% sure why it was happening, I figured out that in my particular scenario I could get it to stop happening by re-enabling the UOM in that particular UOM Class. Like I said, I highly doubt this is your exact scenario, but maybe it will give you some ideas on some more stuff to check.