title: Increasing the speed of Xilinx ISim simulation
body: <p>I have a large ISim design for Spartan-6 using about 6 of the Spartan-6 FPGA IP cores. It needs to run for a simulation time of 13 seconds, but at present takes 40 seconds to run a simulation time of 1 ms. During the 13 seconds it will also write 480000 24 bit std_logic_vectors to a text file.</p>
  
  <p>This equates to running time of 144 hours to run the entire simulation (almost a week!).</p>
  
  <p>Is there a way, for example, of increasing the step size or turning off the settings for waveform plotting etc, or any other settings I can use to increase the simulation speed?</p>
  
  <p>So far I have tried not plotting the waveform, but it doesn't seem to actually increase the speed.</p>
  
  <p>Thanks very much</p>