A new setting in Sytist 0.7.7 in Settings -> Photo Sizes & Defaults is a resize quality. When photos are uploaded they are resized to create the different sizes used.
The resize quality has an effect not only on the quality of the photo but the file size of the photo. The lower the quality value, the smaller the file size which means faster loading.
This setting should be somewhere between 70 - 90.
Here are some examples of a photo uploading with different quality settings.
The original here
http://www.picturespro.com/sy-misc/resize-quality/original.jpg
Quality 70 - 207KB
http://www.picturespro.com/sy-misc/resize-quality/quality-70.jpg
Quality 75 - 228 KB
http://www.picturespro.com/sy-misc/resize-quality/quality-75.jpg
Quality 80 - 260 KB
http://www.picturespro.com/sy-misc/resize-quality/quality-80.jpg
Quality 85 - 305 KB
http://www.picturespro.com/sy-misc/resize-quality/quality-85.jpg
Quality 90 - 384 KB
http://www.picturespro.com/sy-misc/resize-quality/quality-90.jpg
Quality 95 - 556 KB
http://www.picturespro.com/sy-misc/resize-quality/quality-95.jpg
I suggest you do some experimenting on your settings.
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