This paper introduces FocusMetrics XR, a system designed to enhance collaborative analysis in XR environments using three-dimensional gaze visualization. By aggregating users’ fixation data into real-time 3D heatmaps on virtual objects, the system highlights shared areas of attention, improving coordination and mutual understanding during collaborative tasks. FocusMetrics XR integrates the Mixed Reality Toolkit (MRTK) with Photon Unity Networking (PUN) to enable real-time synchronization, ensuring efficient performance in resource-constrained XR settings. A lightweight rendering algorithm is used to visualize fixation-based heatmaps on complex 3D geometries, while an interactive cube tool allows users to focus on specific areas, optimizing computational efficiency and reducing unnecessary tracking. The system is demonstrated through a medical use case involving a 3D heart model. Initial evaluations suggest that 3D heatmaps improve data interpretation and collaboration, leading to faster and more accurate task completion compared to traditional methods. Users particularly appreciated the gaze-sharing feature, which helped align focus during group activities. Applications extend beyond medical diagnostics to education, collaborative design, and environmental monitoring. Future work will explore scalability in larger teams and dynamic environments, supporting more complex multi-user interactions.