"Stephen J. Turnbull" <stephen(a)xemacs.org> writes:
 (Reading of headers is still unconscionably slow for me, but I
 believe that's documented in the Gnus manual for large nnml groups
 because of all the disk I/O needed.) 
What disk I/O?  nnml reads the headers from a single .overview file.
The way I understand it, nnml is supposed to be the "fast" one.
Reading the headers is fairly slow, but its speed has never been
O(n^2).