1. A computer-implemented method comprising: executing, by a host controller server, a query pertaining to at least one virtual machine of a plurality of virtual machines running on a plurality of host computers in a virtual machine system, a query being associated with reporting event data concerning the at least one virtual machine, the virtual machine system comprising the host controller server coupled to the plurality of host computers via a network; providing, by the host controller server, a result of the query to a client of a plurality of clients via the network for presentation to a user in a graphical user interface (GUI); periodically re-executing, by the host controller server, the query to obtain up-to-date information for the at least one virtual machine in the virtual machine system; upon each re-execution of the query, comparing, by a processing device of the host controller server, a new result of the query with a previous result of the query to determine whether the up-to-date information for the at least one virtual machine in the virtual machine system has changed, wherein the virtual machine system comprises the plurality of clients coupled to the plurality of host computers and the host controller server via the network; if the up-to-date information for the at least one virtual machine in the virtual machine system has changed, determining, based on the reporting event data, whether a change in the up-to-date information corresponds to a type of change intended to generate a reporting event; providing, by the host controller server, the new result of the query to the client via the network for presentation to the user in the GUI if the up-to-date information for the at least one virtual machine in the virtual machine system has changed and the change in the up-to-date information corresponds to the type of change intended to generate a reporting event; and refraining from providing the new result of the query to the client if the up-to-date information for the at least one virtual machine in the virtual machine system has not changed or the change in the up-to-date information does not correspond to the type of change intended to generate a reporting event.