This study seeks to investigate the impact of a real-time multi-peer feedback process with the use of a web-based polling software on adult e-learners' learning performance. Two groups of participants with 30 members in each were involved in the experiment. In the two-and-a-half-hour experiment, the experimental group adopted a web-based polling software -- Rain Classroom to carry out the real-time multi-peer feedback activities for the learning of some English infinitive verbs, while the control group was applied the real-time single-peer feedback mode in learning the same content. A pretest, a posttest, a delayed posttest, a questionnaire survey and a follow-up interview were employed as the instruments for the experiment. The results revealed that the multi-peer group significantly outperformed the single-peer group on the delayed posttest, though no significant difference was found in the posttest between the two groups. The questionnaire survey and the follow-up interview showed that the multi-peer method gained great popularity among the participants and could enhance learners' engagement in learning. Other related issues are also discussed.