Hello Nick,
Welcome to the Forum.
First and foremost please check if your computer's config complies with the System Requirements of SSE. If so, try the demo version for starters.
SSE has been performing differently for all its owners. Even those with high end computers have complaints. Many bugs have been fixed through the patches. There is a tendency to compare SSE with other games and expect the same performance but that is not entirely right. Generally speaking, there are a fair number of buyers who have been happy with the performance of SSE.
As I said, try the demo first and satisfy yourself before buying the DVD.
Regards
vin_sun
