Tivo is sluggish

For the last few days I've been noticing that my Roamio is acting sluggish. E.g., when I click the Tivo button it can take several seconds (very noticable delay) in bringing up the screen. And a long delay again in bringing up My Shows. And this isn't an intermittent thing - it is that way pretty much all the time now. This is new behavior.

Has there been a recent software upgrade that might have affected this? Or is there something that can go wrong to give this behavior? I tried restarting it, but that doesn't seem to have helped.