Panel a: absolute RV drift of CARMENES VIS over four years. Detector cryostat sorption pump re-generations are marked withblack ticks. Panel b: temperature of the CARMENES VIS room (orange) and of the VIS optical bench (blue). Panel c: time series of the VIS FP. Object fiber A (black) and reference fiber B (gray). Panel d: relative drift between fiber A and fiber B. Panel e: PTPS computed from panel c. Shaded area: data taken prior to the FP coupling change. Panel f: cumulative histogram of PTPS marked with the 25, 50, 75% quantiles (vertical dashed lines). The median precision of the VIS channel is 1.2 m s⁻¹.