An online environment server hosts an event, such as a class period or interactive entertainment event, in a virtual reality process. Clients are divided into groups as they join the process according to defined group and user profiles and current group capacities. A human host, such as a teaching assistant, may also join each group as a moderator or administrator. Each group member interacts in real time with other group members via electronic chat. Recordings of group sessions may be accessed later by non-group members. The group server is configured such that the group moderator or administrator may control classroom data flow for her assigned group, such as pausing an animated stream of instructor or event input into the virtual classroom to allow classroom questions or discussion, causing the stream to be cached at the system level. Then, the moderator may resume play of the instructional sequence. When resuming play after a pause, the system server may automatically speed up play of the animated input stream from a cache while continuing to cache as necessary, until parity is reached with the current input stream for all groups.