WT already has a config option (log.zero_fill) but it defaults to off and we don't enable it. The interesting thing is that it lets you make a tradeoff between disk bandwidth and write latency. It means that journal files are written twice, but substantially reduces the latency to fsync the journal. I observed significant improvements to ycsb (which is latency bound) by turning that on.

I don't know if we want to arbitrarily make that tradeoff or make it a new easy tunable. A cool way to do it (but much more of a project) would be to do it dynamically based on how much we are limited by write throughput (on EBS we have a hard cap and we can check how close we are to hitting it).