I've been hunting those memory leaks for months now 
The starting point to troubleshoot should be enabling stats: http://hubitat.local/hub/enableStats
Once it runs for a few hours, grab collected statistics: http://hubitat.local/hub/stats
Please post them here, and we can review.
There's a strong correlation between apps/drivers that report long total running times and memory consumption. The fix could be as simple as increasing dashboard refresh intervals, but that depends on what stats say. It could be more involved, but let's try easy pickings first.
BTW, we're working on a easier way to access this information. There's much more troubleshooting value to it than first thought.
Also, event and state history values can be set to much lower numbers unless you have specific uses for them.
