Actually, I have had way more of a speed problem with Simplify rendering. For a long time, I have resized any file that I want to work on in Simplify to 1500 px on the longest side. This makes the rendering of work done in Simplify very speedy. Then I upsize it back to the original file size. This process has also eliminated some of the weird results I would sometimes get; everything would look great inside of Simplify, but when it returned as a Layer in PSCC, it looked radically different than back inside of Simplify.