Forum OpenACS Q&A: Response to db_dfs - simulating "connect by" queries
If all hierarchical searches were implemented with db_dfs, then they would at least work by default, and only those searches that turn out to be too slow would have to be changed.
To quantify the difference: According to a series of tests I have run, the simulation of "connect by" by recursion in the Tcl layer is 4-5 times slower than the original Oracle feature.
I don't know how slow the emulation is in PL/SQL. Has somebody benchmarked it?