Try these things:
- Remove and reinstall Quicktime
- Disable Resample on all clips
- Lower the quality of the preview window
- Purge unused media to help free up resources
- Match Project Properties to your source media
- Disable all start programs from running
- Play around with the Split Screen button above the preview window
- In the Trimmer window, unselect the “Show Video Monitor” button
- Preferences Video Tab: Take your RAM preview to 0 megabytes.
- If you get green clips coming in, select all clips and bring them in to a new project file because the old one is corrupt.
- Make a new folder on your other hard drive and under preferences place all the temp files on there.
- Zoom out
- Press F5 to rebuild peaks, peaks have to be built before importing them on timeline
- Virtual memory to c: on not d: since d has the video files
- stay with 8bit editing and not 32bit. While 32bit editing can offer a tiny bit better visual quality when using plugins or transitions, it is extremely slow to edit as such.
- Set the preview quality (in the preview window) to “preview (auto)”.





