Incompressible two-phase Volume-of-Fluid (VoF) simulations are subject to strict time-step constraints, most notably the Courant–Friedrichs–Lewy (CFL) condition~[1] and capillary time-step restrictions~[2]. In many liquid–gas applications, the flow is in a free-surface regime in which the relevant dynamics are confined to the vicinity of the interface and the heavier (liquid) phase, while the far-field gas remains close to hydrostatic equilibrium. Nevertheless, conventional VoF solvers assemble and solve the momentum predictor and pressure-correction systems on the full computational domain at every time step, incurring substantial computational cost in regions that contribute little to the solution update. We propose a localized predictor–corrector method that restricts the velocity–pressure coupling to an interface-following active subdomain, $\Omega_{\mathrm{sub}}(\alpha)$, constructed dynamically from the volume-fraction field $\alpha$. The active domain comprises the heavier (liquid) phase and a narrow band of gas cells adjacent to the interface, enabling the linear systems associated with the momentum predictor and the pressure Poisson equation to be formed and solved on a reduced mesh. Although described here in a VoF setting, the subdomain construction requires only a scalar marker field and can, in principle, be defined from alternative interface representations such as a level-set function or phase indicator. The method is implemented in OpenFOAM within a PIMPLE-type segregated framework. Verification is performed using classical advection tests and transient free-surface benchmarks, including the collapse of a liquid column and micro-cavity filling. Comparisons against the geometric VoF solver \texttt{interIsoFoam} indicate reduced time-to-solution with only minor deviations in key quantities and interface metrics. Overall, the approach preserves physical fidelity while avoiding costly full-domain solves, and is particularly attractive for problems featuring large quiescent, near-constant-pressure regions with focus on computational efficiency. [1] R. Courant, K. Friedrichs, and H. Lewy, ¨Uber die partiellen Differenzengleichungen der mathema- tischen Physik, Mathematische Annalen, 100(1), 32–74, 1928. doi: 10.1007/BF01448839. [2] F. Denner and B. G. M. van Wachem, Numerical time-step restrictions as a result of capillary waves, Journal of Computational Physics, 285, 24–40, 2015. doi: 10.1016/j.jcp.2015.01.021.