My own personal opinion is that a lot of the earlier projects were fixated on performance at all costs (even when the numbers didn't prove so - always run your

My own personal opinion is that a lot of the earlier projects were fixated on performance at all costs (even when the numbers didn't prove so - always run your own benchmarks) with the heavy downside that you would need to have custom compile/add patches for everything. That's a real non-starter for the vast majority of people out there. There are now at least 3 venture-backed commercial companies working on unikernels today (maybe more), ours being one.