I've graphed the rate of change of the TotalReadLatencyMicros counter over the last 12 hours, and divided by 1,000,000 to get it in seconds. I'm grabbing it every 10 seconds, so I divided by another 10 to get per-second rates.
The result is that I have a CF doing 10 seconds of read *every second*.
Does that make sense?
If I divide it by the number of reads done, it matches up with the latency I'm seeing from cfstats: 1.5ms/read.