An idea to save the bandwidth

[acyk]

Dear sir

I have an idea to save the bandwidth , but I don't know is there have any plugin for this

Our post usually has lots picture in the article , they were saved with attachment system .

User A read this post#123 , first time it shows all pictures ( ex. there are 20 pictures in that article , total size is 1MB ) , then he go away to read other article .

maybe couple minutes later , he comes back , and read that post#123 again to read the reply , but this time he don't need to see all that pictures in first article , he just want to read the reply .

Therefore , everytime he came back for this post#123 , we knew he was read this before , so we don't need to show the picture for him , we just show the link " click here to see the picture ", or put a big button "show all picture" on the top of page .

in this way , we can save lots of bandwidth and the forum will much faster for all of this.

can we do that ?