If those two alarms are FLIRS devices (Frequently Listening Routing Slaves (FLiRS) are a class of Z-Wave devices that are battery powered but wake up every second to check if there is a message waiting for them . FLiRS were initially used for door locks...) your issues could be related to them being offline. Offline FLIRS devices can really blow up your Z-Wave network under certain conditions...
I had a severe hub problem similar to yours during the recent beta which turned out to be caused by a battery powered Z-Wave thermostat when the batteries died and the device fell off the mesh. Once the device was offline, havoc ensued, as other devices trying to communicate w/an offline FLiRS device is not good for your mesh:
From @bcopeland: This is a LSS (FLiRS) device .. So sending a command to it while not powered would cause a flurry of activity while it tries to wake it through the previous route and multiple other routes after it doesn’t reach it through the expected route..
Your problems might be exacerbated after an update/reboot. So maybe put your alarm devices back online (or fully exclude them) and do a shut down/pull power/wait 30s/reconnect power and let things run for a while. 
