My preference is to have unoptimized by default, unless there is only a negligible difference in compile-time between the two options. I mostly don't need optimized programs while I'm developing them.
Alternatively, don't have a default and let people opt-in to whatever default they like. That forces people to actually make a choice, instead of being lazy and publishing poor benchmarks without having even looked up what optimization knobs there are to turn on or off.
Alternatively, don't have a default and let people opt-in to whatever default they like. That forces people to actually make a choice, instead of being lazy and publishing poor benchmarks without having even looked up what optimization knobs there are to turn on or off.