Solid Opinion has improved the response time of their system. Once some reintegration work is done, Nextbigfuture will switch the comment system back.
It was previously believed that WordPress comments would be better, but this has proven not to be the case. This was surprising since WordPress is such a popular system that the expectation was that the comment system would work. Other websites with more traffic have used WordPress comments without significant reported issues.
Hopefully this will be resolved in a week or two.