hi i installed sims 3, and all stuff packs and expansions onto my external hard drive and it all works fine except i noticed it slowed the game a little bit and was especially noticeable when loading new data, so i decided to just move it onto my main hardrive whenever i want to play however the game wont start, using the launcher or the S3E03 exe

i believe because its not in the folder i installed it to, and i tried to find a txt file which dictates where the exe or launcher looks for the game files but i couldnt could someone tell my how to fix this im running windows 7 btw

Uninstall and reinstall to the hard drive would be the most prudent fix available. Simply copying/moving game files probably isn't the best idea.

yeh im hoping to have to do that as a last resort because, reinstalling is a long process and having to do that every time i want to play is going to get annoying

You shouldn't have to reinstall every time you want to play. Just the once. You just need to make sure that any removable devices (like your external hard drive or any USB memory sticks or virtual drives) are put back in the same order so the drive letter doesn't change.