Buildism Mobile Version?

[Paradox]

MAC OS X Handles Multi-tasking better that Win7.
Also Windows XP > Windows 7
Windows Vista

That really depends on what specs you have. The more RAM/Memory you have, the better your computer is at multitasking. I have 6 Gigs and I can run Pandora, Minecraft, Buildism (With a bunch of threads open in tabs), another 3D game and Skype all at the same time without slowing down.