We host hundreds of thousands of user uploaded images. Our site averages around 5 million pageviews per month. Optimization is key. And mobile users should expect us to be good stewards with their data limitations by optimizing as best we can. Sorry to hear you're not interested in helping to conserve resources and bandwidth.
Our forum actually outperforms Facebook on just about every meaningful level except for image upload ease and efficiency.
I'd really love to see your server statistics to see how your site would be out preforming the entire Facebook platform; Alexa
Ranks Facebook as the #2 website in the world; comparing those figures to what they list on your site (in the top 1mil sites) I am noting a discrepancy.
But, at the issue at hand, the upload script in the UBB does not parse images seperately from how it handles other file uploads; in fact, while brainstorming with id242 earlier it's come to light that the current upload system probably needs attention in of itself in the future.