Well there is Windows LIVE
Movie Maker and Windows Movie Maker 2.6 but I have never heard of Windows Live Movie Maker 2.6
?????? Maybe you got the title wrong.
In my view, Windows Live
Movie Maker sucks and that's what I keep saying in this forum. Its not as good as the standard Movie Maker and it doesnt even have a timeline which is a huge drawback and if this is the kind of movie maker you are saying, then the lagging only adds up to the list of problems with it.
Windows Movie Maker 2.6 (not from Windows Live Essentials) is much better and I used that on Windows 7 to make videos which I later uploaded to Youtube. It has flaws but works just fine on Windows 7 and I love it. If you are not using this version, please switch to it now.
You may also try running the program in Compatibility Mode