Here's an idea for a model: Use logarithmic decay of speed down to the rate limit, the first bit of browsing is a fast preview. As you continue browsing a pop

Here's an idea for a model: Use logarithmic decay of speed down to the rate limit, the first bit of browsing is a fast preview. As you continue browsing a pop up explains that you're being rate limited and that you can pay if you wish to resume unlimited browsing speed.