I appreciate your work, but you're not being very honest with your claims.
nnn is not keeping information about 400K files in memory in that benchmark. As a result, the rescan is necessary when changing directory. The rescan may be fast in many cases and in some cases it may even be what you'd want, but I can also name many cases where you certainly won't want it (large NFS mounts being one example).
Sorry for the pedantry. I spent a fair amount of time optimizing ncdu's memory usage, so I tend to have an opinion on this topic. :)
nnn is not keeping information about 400K files in memory in that benchmark. As a result, the rescan is necessary when changing directory. The rescan may be fast in many cases and in some cases it may even be what you'd want, but I can also name many cases where you certainly won't want it (large NFS mounts being one example).
Sorry for the pedantry. I spent a fair amount of time optimizing ncdu's memory usage, so I tend to have an opinion on this topic. :)