The first proposed component, called Enhanced Client Access (ECA) ([PERSON] et al., 2019), extends NAF with the ability to monitor and control client apps sharing a virtual scene. The second one is 6-DoF SMC (Smartphone Motion Capture) ([PERSON] et al., 2018), which addresses the lack of Six Degrees of Freedom (6-DoF) motion tracking for smartphones. The 6-DoF motion capture is supported \"out of the box\" for VR headsets, such as Oculus Touch, Oculus Quest, HTC Focus HTC Vive or Windows MR-compatible devices ([PERSON] et al., 2019). However, it is not supported for the stereoscopic mode in smartphones, which is a significant disadvantage as interaction with less than six DoF rules out all-natural movement in XR. Smartphones offer 3-DoF capture with the rotational motion tracking but not the translational one. Thus, the users may turn but not move from place to place in a virtual scene. They need additional devices to move, such as gamepads or joysticks, which are less natural for such interaction. The third proposed component, named HoloGOM ([PERSON] et al., 2018), deals with Microsoft (MS) HoloLens, where available web frameworks do not include access to gesture processing. Therefore, the users are limited to interact only by the clicker device and object manipulation by hand tracking is not available. HoloGOM solves the issue by supporting free-hand manipulation and tap gestures. While developed for A-Frame, the second and third component can be used for virtually any application, implementing WebXR. All three components are incorporated into the client-server architecture of A-Frame and NAF (Figure 1) to offer a more natural user experience in shared virtual environments (scenes). A-Frame and NAF provide the virtual scene and means to share it between multiple users: a server machine (SRV in Figure 1) runs a web server application (app) that hosts all the resources for client apps and runs the server-side modules of NAF. Each user device (PC, PH or HL in Figure 1) runs an instance of a web browser with a client app that renders the shared virtual scene using A-Frame modules and client-side modules of NAF. NAF keeps track on networked entities, which represent users and shared objects in the scene. Thanks to this, a user can see avatars of other users and shared objects in the scene. ECA runs inside both the server and the client apps and allows to rise mutual awareness of users sharing the scene by providing access to their positions and other properties. 6-DoF SMC and HoloGOM run inside the client apps on the corresponding devices to translate the user movement in a real environment to the virtual one. The aim of the performance evaluation of the proposed components was to find answers to the following research questions:  
* RQ.1: How does the added functionality, implemented in the proposed components, affect the A-Frame and NAF performance under different loads? * RQ.2: How do A-Frame and NAF perform under different loads on mid-range hardware and MS HoloLens? The evaluation was carried out in the form of three sets of experiments, each focusing on one component. To eliminate the interference from internet traffic, the experiments took place in a dedicated local network environment, but with Internet connectivity available for all devices. In principle, the network environment resembled the one shown in Figure 1. Personal computers (PC), representing users in a shared virtual scene, were connected, via a switch and to a server (SRV) running the web server app. MS HoloLens (HL) and a smartphone (PH) were accessed through a WiFi router, connected to the same switch. By the different loads we mean different number of active users, sharing the scene. Each set, except of the one for the MS HoloLens component, consisted of experiments with 1, 5, 10, 15 and 20 users. Only 1, 5 and 10 users were used for MS HoloLens as the performance dropped to unacceptable levels with a higher number of users. Two performance measures  
Figure 1: A-Frame, NAF and the proposed components in a typical configuration. were recorded.