To fully consider the influence of time-varying pressure and film thickness, the transient Reynolds equation is typically employed for numerical computations in the analysis of gas bearing-rotor systems. Solving the transient Reynolds equation is complex and time-intensive. To enhance computational efficiency, this paper presents an optimized algorithm, termed as the equilibrium position (EP) method, which leverages the solution of the steady-state Reynolds equation to analyze the axis shift induced by rotor imbalance. By neglecting certain transient terms while retaining the essential physics, the proposed method achieves high computational accuracy and significantly reduces computational time. The computational errors are evaluated, and comparisons with orbit method simulations demonstrate the method's efficiency and accuracy. In applications such as predicting rotor vibration amplitude or estimating unbalanced forces during ultra-precision machining and rotor design, the EP method offers a streamlined computation process without compromising on result fidelity.