first of all id like to introduce myself as this is my first post. im oliver and i have been interested in lighting since i was tiny

anyways my problem

iv been using freestyler for a long time now and love the program. i used to use it all the time with a velleman usb dac and a small amount of lights. then i bought a lighting desk and started to program on that for a few years. the desk was fantastic and had fixture files and was pretty advanced, the only problem back then with both freestyler and my desk was they didnt have FX generators so took a long time to create half decent shows. then found that freestyler had added a fixture generator so tried it on 4 moving heads and it was amazing. i love using it and helps me out so much to create a fantastic show. i recently bought another 6 moving heads and it works great with all of them.
im doing a full lighting show for a festival so im using all of my equipment so started testing last week, iv setup all the movers which work great, then i hooked up my 4 x abstract xp2s, my 4 x martin 812s and 4 x chauvet intimidators. all of them suffered from a terrible stuttering when trying to use the fade feature and when scrolling round with the pan tilt.
i decided to do some testing so hooked 1 martin up and the problem was still there, i decided to remove all the other fixtures off the workspace and controlled 1 fixture and it was pretty smooth and controlled i then started adding fixtures until id added about 6 or 8 and they gradually started stuttering worse with every fixture.
its extremly strange cause the movers work fine and all other fixtures are perfect but every scanner is stuttery. its not the laptop as im using a quad core 2.3ghz, 4gb ram laptop. i tried using the scanners on my desk and they worked fine.
im looking to try and use all the fixtures on the laptop and cant handle the stuttering as it looks awful can anyone please please please help
thanks so much in advance
oli