Maybe pressurize the tires with helium?
My 19.5" 2005 Blizzard weighs in at 24.5 pounds with a Magura Ronin 80mm fork, RF ISIS Turbine cranks, XY0 seatpost, 120mm Deus stem, Syncros flat bar, XTR R Der, 7 speed thumbshifters, Marta discs, Hope XC disc hubs/X317 rims, Nokian NBX 2.1 tires, Selle Italia Flite seat.
My 2000 Vertex weighs in at 22.8 pounds with Fox F80RLT fork, Mavic Crossmax XL wheels, Avid Ultimate V-brakes and levers, SRAM X.0 rear derailleur and trigger shifters, XTR front derailleur, Conti Vapors, Race Face Deus cranks, XY0 seatpost, 120mm Deus stem, Syncros flat bar, Selle Italia Flite seat.