Filemaker's odbc access is inefficient, that's why it is slow. We run odbc between MySQL and FMS10 on OSX. Having the exact same issue as you. It's not the odbc layer, it's just FM make really bad calls.
Until they program more efficient ways of handling the data, you're not going to see any improvement. If you want to know what the thing does, run a query log on your oracle server and see all the extra stuffs that FM do to fetch a single result and you'll know why it's slow.