1. Start up CuteSITE Builder (or Trellix) and open your .tlx file
2. Click on File > Save As - and enter a new name
3. Exit CuteSITE Builder.
If you now view the file sizes of your original and new files, you may be pleasantly surprised to find that the size of you r file has been reduced drastically.
What happed? Well, as you add and delete pages and images within CuteSITE Builder / Trellix, those deleted areas remain, taking up space. Doing a File > save As essentially reclaims that wasted space.