I assume it’s this bike?
Frame: HPA Ultralight, Advanced Hydroform, Triple Butted, ETC 4-Link, ISCG mount, AXH
Rear Shock: Manitou Radium Pro DC RL, 216x64mm, Rebound, Lockout
Fork: Rock Shox Pike RC Solo Air 27.5, 15QR Maxle, tapered, 160mm
Headset: FSA Orbit 1.5E ZS, top zero-stack 1 1/8 (OD 44mm), bottom zero-stack 1 1/2 (OD 56mm)
Stem: Race Face Chester 31.8mm
Speed: 20
Front Mech: Shimano Deore FD-M616-D, direct mount, Down Swing
Rear Mech: Shimano XT, RD-M781-GSL, Shadow, medium cage
Shifters: Shimano Deore SL-M610-I Rapidfire-Plus
Chainset: Shimano Deore, FC-M615, 24/38T, 175mm
Front Brake: Formula C1 hydr. Disc 203
Rear Brake: Formula C1 hydr. Disc 180
Rims: CUBE EX 23.7, 584x23C rim, 32H
Front Hub: CUBE EX 23.7, 100x15mm
Rear Hub: CUBE EX 23.7, 142x12mm
Tyres: Schwalbe Hans Dampf 2.35 Front Schwalbe Hans Dampf 2.35 Rear
Seatpost: CUBE Performance 31.6*400mm
I’d look at changing wheels (maybe to Arch Ex on ProII) and run tubeless, going 1×10 and changing the deore cassette for XT/SLX. You could make all those changes for £350 ish and knock off at least 1.5 kg.