mutt imap header cache benchmarks

tested with same .muttrc and /etc/mutt/Muttrc and with dovecot's header
cache switched off. The local machine runs the server, the remote one is on
the same LAN.
                                                                                                                              
locally
                                                                                                                              
$ time mutt -e 'exec exit' && echo "^ no header cache"
                                                                                                                              
real    0m1.061s
user    0m0.495s
sys     0m0.066s
^ no header cache
$ time mutt -e 'exec exit' && echo "^ writing header cache"
                                                                                                                              
real    0m1.393s
user    0m0.639s
sys     0m0.214s
^ writing header cache
$ time mutt -e 'exec exit' && echo "^ using header cache"
                                                                                                                              
real    0m0.667s
user    0m0.407s
sys     0m0.101s
^ using header cache
                                                                                                                              
remotely
                                                                                                                              
$ time mutt -e 'exec exit' && echo "^ no header cache"
                                                                                                                              
real    0m0.916s
user    0m0.215s
sys     0m0.050s
^ no header cache
$ time mutt -e 'exec exit' && echo "^ writing header cache"
                                                                                                                              
real    0m1.102s
user    0m0.335s
sys     0m0.120s
^ writing header cache
$ time mutt -e 'exec exit' && echo "^ using header cache"
                                                                                                                              
real    0m0.890s
user    0m0.195s
sys     0m0.015s
^ using header cache