text: It depends what type of laptop you are comparing it to because there are a few different types ie desktop replacements, thin slim line ones, buisness ones etc.\n\nAlso it depends on the spec of the desktop and laptop that you are comparing because obviously that will be a big determing factor of what the difference between them will be like.\n\nHowever at a rough guesstimate ( love using that word lol )\n\nI would say about 15 - 20 % slower on a laptop then on a desktop because you get the slower hard drives ( and if you are running off of the battery then it goes quite a bit slower because there isnt as much power as running off of the mains ).\n\nThere will be a lot of other variables that will determine the differences as well ie the motherboards chipsets on each of the machines, the amount of RAM, the speeds of the RAM , front side bus speeds on the CPU, etc etc etc. It goes on and on.\n\nWhat sort of things will you be doing on the laptop that you normally did on the desktop ?