1. A method for executing a plurality of threads in a multithreaded processor, the method comprising: defining a plurality of threads, wherein each thread executes a sequence of program instructions and at least a subset of the plurality of threads are of different types; fetching a first instruction for a first one of the plurality of threads; fetching a second instruction for a second one of the plurality of threads, the second thread of a first type comprising a vertex thread type; issuing the first instruction, wherein the first instruction has a latency period associated therewith; and during the latency period associated with the first instruction, issuing the second instruction based at least in part on a priority ranking associated with the first type, wherein the first instruction and the second instruction are issued in an order independent of an order of fetching the first and second instructions, and wherein the second instruction is issued before one or more other instructions ready to issue for a longer duration than the second instruction, the one or more other instructions for a thread of a second type comprising a pixel thread type, wherein the pixel thread type is associated with a lower priority ranking than the priority ranking associated with the vertex thread type.