How do you create a fastest browser in the whole world? You just CACHE everything in a dumb way!
I just ran into a problem when a client reported anomalies with shopping cart functionality in a project I'm working on. Apparently when you add a product to a cart using Opera and then just navigate to a shopping cart page you see the (client) cached version of that page. If you refresh you see the actual version, then you remove a product from the cart using POST and you still see the actual version, then you just navigate to cart.aspx page and you see the cached version again.
I had no time to investigate the deep causes of this behavior but it looks like Opera by default is pulling from cache any page requested with GET and having no question mark in the URL if it was already requested less than 5 minutes ago.
Since I had no time to research the roots of this behavior I just solved (hopefully) the issue by adding
<%@ OutputCache Location="None" %>
to every sensitive aspx page.
Maybe I should do this all the time just to stay safe but neither IE nor Firefox were behaving in this crazy manner without this. So I'm guessing it's just because they are not after the "fastest browser on the market" crown and can justify creating a smart caching system sacrificing "speed".
Update: No caching results in back button not working... hmm... I hate these issues...