Video editing is resource intensive. What are your PC's specs: CPU, GPU, free space on the drive, memory?
Close all other programs that might be running in the background. Lower the preview resolution (right-click in the preview window to see that option).
Under the OPTIONS|EDITING menu, try toggling the HARDWARE ACCELERATION choice to its other state.
Are you using the current version of Videopad? If not, give it a test.
If your project is reasonably small, place it on the timeline and then click FILE|SAVE AS PORTABLE PROJECT.
Upload all the files that result to DropBox, Google Drive, MS OneDrive or the like. Or zip them and upload the zip file.
Make the link public and post it here. Someone will check it out.