Mild Cognitive Impairment (MCI) is a critical transitional stage between normal cognitive aging and dementia, making its early detection essential. This study investigates the neural mechanisms of distractor suppression in MCI patients using EEG and behavioral data during an attention-cueing Eriksen flanker task. A cohort of 56 MCIs and 26 healthy controls (HCs) performed tasks with congruent and incongruent stimuli of varying saliency levels. During these tasks, EEG data were analyzed for alpha band coherence's functional connectivity, focusing on Global Efficiency (GE), while Reaction Time (RT) and Hit Rate (HR) were also collected. Our findings reveal significant interactions between congruency, saliency, and cognitive status on GE, RT, and HR. In HCs, congruent conditions resulted in higher GE (p = 0.0114, multivariate t-distribution correction, MVT), faster RTs (p < 0.0001, MVT), and higher HRs (p < 0.0001, MVT) compared to incongruent conditions. HCs also showed increased GE in salient conditions for incongruent trials (p = 0.0406, MVT). MCIs exhibited benefits from congruent conditions with shorter RTs and higher HRs (both p < 0.0001, MVT) compared to incongruent conditions but showed reduced adaptability in GE, with no significant GE differences between conditions. These results highlight the potential of alpha band coherence and GE as early markers for cognitive impairment. By integrating GE, RT, and HR, this study provides insights into the interplay between neural efficiency, processing speed, and task accuracy. This approach offers valuable insights into cognitive load management and interference effects, indicating benefits for interventions aimed at improving attentional control and processing speed in MCIs.