Items that you store in memory with mod_perl are only available to the same
apache process, so that may not help you much. You could try using
to make
your datastructure available across processes. This can buy you a lot
of performance, but has a lot of risks (i.e. if you reboot your
system the data in shared memory is gone, unless you have a facility to write
it to disk). Your best bet is probably to use a real database (Postgres, mysql, etc...)
and if it isn't fast enough for you then consider some sort of
in-memory caching. mod_perl can buy you a lot with traditional databases
performance wise (presistant cached database handles, etc..)