Our file sizes are larger than Adobe Acrobat created at 1.5 or above since the highest 'CompatibilityLevel' we support is 1.4
Enhancement still missing in Ghostscript 9.03
Fixed in commit 1a98e7bf843e7845d5c6f5c19449f4385d6e5543 and updated in 5ff71a3e57050f9bf543999fd697e861e89c28ed for PDF/X and PDF/A output