Any video I am working on I get stilted movement

Any new video file or exiting file I work on plays in a jerky movement.I’ve tried changing video speed but no change in viewing problem. I’ve never had this issue before.It seems to have started when I installed the latest version.
I have uninstalled program and reinstalled and no change. Any suggestions would be great. I am reasonalbly new at video production.
Thanks
Peter

Does this answer your question?

if not, do as Hudson advises and provide the necessary information for someone to be able to help you.

If you are on macOS, this is a known bug (not new to version 19.02.28) and you simply need to restart the app.

Thank you for the advice but not using macOS and I have uninstalled app and reinstalled but no change to the problem. As Christan stated video can be exported but a 18min clip at 30% takes about 2hrs but video runs ok on any video player once exported.
Peter

Software-based video encoding is heavy especially for H.264 (default), HEVC, and VP9. That is just the way it is based on your system, and it is not a bug. If you can get hardware encoding working, then it may go a little faster. Just click the checkbox in Export to enable it, look for the status messages in the middle of the screen for a few seconds to see what it found, if any.