Using Cri/oFlex® instead of conventional semi-rigid coax cables allows us to increase the cabling density by an order of magnitude without thermally overloading the cryostat. The flexible stripline thermalises with a time constant of 0.28 ms, almost a factor of two faster than cryogenic coaxial attenuators in a similar setup. This increase in cabling density without heating up the system also does not compromise on performance: no detrimental effects on the superconducting device were observed and the residual photon population remains below 3.5 x 10^-3 photons.
