More information would include
- Shotcut Version (Click on Help, then About Shotcut)
- Latest version of Shotcut is here.
- Video Mode used (Resolution/FPS)
- Source Video/Image properties (Resolution/fps)
- Screenshot of entire Shotcut window with all tracks visible if using the timeline.
- Filters used and their settings, especially on the lone PNG image you’re using.
- Operating System (Windows/Linux/Mac)
- Computer specifications, including drive information (HDD, SDD, NVME).
- Drives used for source files like USB, Cloud, or just the drives on the computer.
- Running Anti-virus? Does it lag with Anti-virus off?
- Minimum specifications listed here.
- Did restarting your computer clear up the lag?
- Any additional steps you have taken to resolve the issue yourself.