What is the speed of the person you are downloading the movies from? If you chose someone who shows modem alot of times it will be slower then someone who has a T3 or higher beside it. What is your download speed of limewire set at? Take me for example, I have been downloading a file for 3 days now. But I am on dialup and very slow. I try to download from people who have high settings. Not sure about the porn, but my opinion is that the reason it downloads so fast is because it is usually just a small trailor or version of a film. therefore it isn't very large and doesn't take long to download. I am sorry I couldn't be of more help. Hopefully someone can help you more.

good luck,
moe