title: grid of 30 images to fade in/out acording to category clicked - jquery fade
body: <p>Hi I have a grid of around 30 cells each with two images, a plain and an active.</p>
  
  <p>Next I have a list of categories, which are assigned to the cells according to their content (wordpress generates these).</p>
  
  <p>Once a category is clicked I need all of the cells which are relevant to that category to fade in or remain active and all of the cells which aren't in that category to fade out.</p>
  
  <p>I have wordpress adding relevant classes to the tiles for categories.</p>
  
  <p>I have a working version of this but it's really slow and I've written much more code than seems appropriate.</p>
  
  <p>Can anyone set me in the right direction?</p>