  Frequency-domain multiplexing is a readout technique for transition edge
sensor bolometer arrays used on modern CMB experiments, including the SPT-3G
receiver. Here, we present design details and performance measurements for a
low-parasitic frequency-domain multiplexing readout. Reducing the parasitic
impedance of the connections between cryogenic components provides a path to
improving both the crosstalk and noise performance of the readout. Reduced
crosstalk will in turn allow higher multiplexing factors. We have demonstrated
a factor of two improvement in parasitic resistance compared to SPT-3G
hardware. Reduced parasitics also permits operation of lower-resistance
bolometers, which enables better optimization of R$_{\rm{bolo}}$ for improved
readout noise performance. The prototype system exhibits noise performance
comparable to SPT-3G readout hardware when operating SPT-3G detectors.
