Reduce image resolution before creating the PDF
Compress images inside the PDF
Convert images to JPEG instead of PNG when possible
Remove unnecessary pages
Delete unused fonts and embedded objects
Use “Save As” or “Optimize PDF” in your PDF editor
Lower the quality setting when exporting to PDF
Flatten transparency and layers
Convert scanned pages to grayscale
Use OCR only when needed
Remove bookmarks, comments, and annotations
Avoid embedding full fonts if not required
Split large PDFs into smaller files
Use a PDF compression tool or online compressor
Recreate the PDF with smaller source files
Export text as text instead of images
Reduce the number of vector graphics if possible