When you drop a clip? I'm not sure what you're saying. When is it shuddering?
2.7k video is 2704x1520, which is not a resolution that is supported by Premiere Elements. Premiere Elements can edit 3840x2160 4k or 1920x1080.
Look under the program's Edit menu. What is listed on the General page under Project Settings? This is the resolution your project is set to.
As I've said, 2704x1520 is not an available setting for a Premiere Elements project. If your project settings do not match the specs of your video, you will get compromised quality and performance, which is likely what you're seeing.