Maybe it's fixed with this version, but we've seen kernel pauses on the order of minutes under high memory / OOM situations, with ZoL trying to get memory.
What was your setup like? I've encountered similar - the cause ended up being a mix of xattrs (I don't use them so I just disabled the feature) and needing to tune zfs to be less aggressive handling my consumer-grade disks.
I run a 10 disk raidz2 array on a box with 4G RAM. If I'm running many other things on that box, memory gets very tight, and it swaps occasionally too. I've not seen kernel pauses on FS accesses though.
