I have a cloud of meraki MX64 one hub three spokes.
do you believe that when there is a Meraki (AMP, signature or other) from the cloud the uplink traffic is delayed?
I tested that are not the server provider and the packet latency between auto VPN nodes remail very low.
The feeling is like if the meraki is busy to do other and cloud is not able to get information or really it delays packets for few seconds of this uplink traffic to the clients. (annexed the effect)meraki uplink gap
in the photo the primary link (management) is the WAN2 the other service provider didnt produce this effect.
Meraki employs an Out-of-band architecture which treats control plane and data plane traffic separately. That being said, when there are updates to AMP signatures, content filtering category updates, that might take a little of your uplink traffic (however, user traffic should have their own prioritization and shouldn't be affected as long os proper QOS policies are in place to identify and prioritize data).
These updates in themselves are very minimal in size and shouldn't take much of the bandwidth to cause a significant effect on the user traffic. That being said, you can control these list update intervals, under traffic shaping page, you can set them to renew either every hour, every day or every week. I hope this helps.
Here is a good read about Meraki's out-of-band architecture if you are interested.