The reduction in snjp4’s block rate from around 1.7 blocks/s to around 1.5 blocks/s is indeed related to one replica becoming unhealthy around 2025-08-18 20:00 UTC.
And then, since 2025-08-19 15:30 UTC there’s a persistent backlog (again, across all canisters on the subnet, so impossible to pinpoint) of around 200 canister messages). Which (if in your canisters’ input queues) may account for the high latency you are observing.
Same as before, the subnet has a slightly reduced block rate (1.5 blocks/s), but it’s not enough to actually affect the measured end-to-end latency of the average ingress message, which stayed consistently under 1.2 seconds for the past week (consensus takes slightly longer whenever the missing replica is designated as block maker, but that simply results in the block spending less time backlogged before it’s executed). And the average round execution time also stayed relatively constant over the past week, at around 300 ms.
As said, canisters are (single-threaded) actors, so a backlog of messages in input queues implies extra latency (because all already enqueued messages have to be executed before a newly received one can be).
(As for the spike and dip in block rate, that can still be observed on the public dashboard, but nothing like it shows up on either of our internal monitoring databases. So it’s likely an artifact of the public dashboard metrics outage from last evening.)