You need columnstore storage and a reasonably mature query optimizer to get good results on TPC-DS. TiDB is lacking both right now.
TiDB developer here, we're working on columnstore for TiDB, will release in the near future. On the query optimizer side, I think in TiDB 3.0, TiDB's optimizer has given the best execution plan for most of the TPC-H (TPC-H 50G) queries. But we've never tested on TPC-DS yet.
We just did a TPC-C test on a 3 nodes TiDB3.0 cluster with similar hardware like r3.4xlarge, the result is:
5000 warehouses, TPmC is ~38K.