Step 1:  Create a blank 400px by 400px document and fill it with a solid black colour. Run the Filter > Render > Difference Clouds command from the main menu and keep re-running it until you end up with a satisfactory cloud (the clouds themselves are randomly generated each time).

NB.  Bigger images tend to work better with this technique, so start large and crop your results later if necessary.  

Step 2: Now select Filter > Blur > Radial Blur and duplicate the settings on the left.  Don't feel tempted to increase the quality, as it also blurs the effect - we'll handle the graininess in the next step...

Step 3: Press OK to render the blur effect, and then repeat step 2 again, this time with the amount set to 40, and the quality set to best.  Once this is done, run Image > Adjustments > Auto Levels to increase the contrasts of the warp.

Step 4: Looking good!  All good warp effects need a little colour, though, so go back to the menu and choose Image > Adjustments > Hue/Saturation. Now all you have to do is click the colourize checkbox and vary the Hue setting until you find a colour of your liking.   And there you have it - a warp-speed effect of your very own!

Variations: This technique may look rather simple but it is, in fact, extremely flexible.  For a slightly different texture to your warp, run the Filter > Pixelate > Mezzotint command between steps 1 and 2 of this tutorial.  The filter drop-down menu has quite a few options to play with, but my favourite is the 'long lines' option, which helps create the streaky effect opposite.