Originally posted by stevebrot Perhaps I am a perfectionist, but my opinion is that any compression of an image for sale or professional display (thumbnails excluded) should be the done by the photographer. That is one reason why I don't upload to Pentax Forums. Additionally, it is my opinion that 25% compression (the 75 setting) is too high regardless of the tool used.
The tool definitely matters. For example, a "75" in Lightroom is pretty low on the compression scheme, closer to a 90 in other programs.
It's always a balance between speed and quality. There's no one right answer on the best balance to hit, and I think it's worth trying out the different settings to see what works best for your purposes. I'm not at all opposed to less compression, but keep your website visitors in mind, and how they're likely to be browsing your images.
Another interesting compression discussion with lots of examples, for Lightroom users:
Jeffrey Friedl's Blog