I don't know how far you want to go money wise, but the first thing I'd do is lose that 11-34 cassette. Maybe tighten it up with a 12-26 or 12-23 pg950 or similar.
Do you intend to go narrower than 32mm for tires? I'm sure whatever rims you have now will work fine down to that.
Off the shelf, don't know what you'll find that will be substantially different weight wise than your current wheels. If you must, you could always go custom. Velocity offers several nice, low weight rims: Aerohead, Fusion, and AeroHEAT. Velocity does custom wheels, too. They could lace your choice of rim to one of their many hubsets with butted DT spokes. Many other builders, too.
Gearing, choice of tire, and locking out the fork will probably make the biggest difference.