I am running off a Mac quad pro 16 gig of memory and have never had a problem with you tube except on my old windows machine, it was maxed out on front side bus/hard drive etc...but when my memory got to full from music files it would interrupt my computer playback, especially on video applications, when I cleaned it up and defrag the system you tube would run better, you might need to get an external hard drive note book which is what I had to do to free up and store my music files to make things run better, I use a western digital that although Mac doesn't read everything windows, I transferred it to my mac because I had some files that I saved and wanted to be able to bring them to Mac.