as for sybase beeing faster: MS SQL server long ago (1 year?) outperformed oracle 8i. See TOP DB ratings on internet. (HW used for benchmarking could be an issue as well )
MS SQL server is derived from sybase.

As for methods how to do this, then think about:
1) fixed row size
2) various denormalized summaries, e.g. in b-tree index can contain number of rows per particular key or per particular b-tree vertex for summary queries.
3) commit/rollback implementation: oracle is optimized for insert/update (see block cleanout issue). Next thing is that getting block in query mode is pretty expensive as rollback segments has to be visited.
Some systems just block select(at least MS SQL srv version 6? did that for me) , while oracle not, just gives ora-01555 sometimes, but this can be managed via rollback segments.
4) quite advanced optimization and/or HW. A time ago I've been surprised by AS400 DB performance.