The BlueStacks software is very lightweight and doesn't take up too many resources from your CPU that it should noticeably slow down. However, when you're playing data-heavy games or have multiple games running at the same time through the Multi-Instance feature, it could slow down your computer. To avoid this, BlueStacks has an Eco Mode that can be enabled which saves on RAM, CPU, and GPU usage so that your computer will continue to run smoothly and without any issues.