Many pictures on web pages are heavily compressed to make them smaller. The smaller they are, the faster they download.
Can you post a link to one site that you are having trouble with, as it may well be that the pictures that are poor quality for you are just poor quality pictures to start with.
To post a link, just copy the address from your web brouser, and paste it into the reply box.
If you use an internet accelerator, such as On Speed, this will result in a degradation of image quality, as the speed increase is achieved my compressing the data even further. The nigher the level of compression, the poorer pictures look.
This picure look fine to me. click here
How does it look to you?