Thanks, I totally forgot about pdqsort! If I recall correctly, it's partially based on blockquicksort, but includes a lot of other improvements. It's a very interesting algorithm, much faster than introsort etc. However, I believe that IPS4o is still faster overall (I think I asked Sascha, one of the authors of IPS4o, about this a while ago, but I don't have any measurements at hand), even before accounting for IPS4o's parallel implementation. You should definitely check out both :)