If I've understood the question correctly I'd be looking to export my Jpegs optimized for the web before uploading. I use Lightroom rather than Aperture but I guess they both have a similar output option.
What i do is export as 72ppi, quality 70% and re-sized to long edge say 1200px or whatever is appropriate to the web destination.
This gives me a typical Jpeg from my D600 of about 120kb on average. Original sized Jpeg's will be simply enormous in comparison.
This also negates the recipient website from further compressing my files leading to better online quality (think Facebook uploads etc)