I am not sure how possible this is (or if it has
already been thought of) but I thought I would suggest
it anyway.

It would seem that speed will always be an issue given
the web based nature of the project.  Would it be
possible to have the API's available to local clients
somehow.  So we could have for example have a native
windows client able to interact through the
phpgroupware api's to the mysql database.

Maybe in we could then have a replication feature like
lotus notes which could replicate data to a locally
running mysql database.  I would think then that
phpgroupware could compete more fully with lotus notes.

My ignorance of the whole project is probably showing
but I hope this is of some help.

Chandra