Is There a Single Virtual Reality Generator?

The heart of a virtual reality generator is its computer. The question of what environments can be rendered in virtual reality must eventually come down to the question of what computations can be performed. A given virtual reality generator will not be able to perform unlimited amounts of computation per unit time. Will this not limit its repertoire? If an environment is so complex that the computation of what the user should be seeing one second from now takes the machine more than one second to compute, how can the machine possibly render that environment accurately to achiev universality? But i mu well just pick upa couple of short paragraphs here, which ar speak about the limitations of computers, the way in which computers must be limited