Cheers for the feedback guys. This is what I've got in top in a Lubuntu vm:

PID     USER      PR  NI    VIRT        RES      SHR    S %CPU %MEM     TIME+ COMMAND  
17833 user      20   0 1656724 116332  59736 S   99.7     4.7       8:55.76 silk-qt    


I checked in a second Lubuntu vm on a different machine and was getting the same thing, and it was hovering at around that level for most of the time the wallet was open (fully synced). It is a weird one. I guess if it isn't happening to anyone else it must be something on my end. Only wish I knew what.