I just replaced a RB493G running 4.17 for a RB850Gx2 running 6.27. The configs are the same between devices however the CPU usage has large spikes as you can see on the Usage graph attachment
Usage Graph.PNG
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If you look at the Normal CPU attachment this shows how the CPU usage is normally
Normal CPU.PNG
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When I open the device settings page in The Dude I get around 40-50% CPU usage jump for up to a minute that shows up in the Profile tool under Management
High CPU.PNG
. This did not happen on the 493G or any of my other Routerboards running 4.17.