It's not clear from your post if you are using a BrowserField, or calling the native browser. In either case, caching is already done for you.
If you are using HTTPConnection and a GET, over a BIS or BES connection, there is a certain amount of caching that occurs over the infrastructure. Usually, the goal is to defeat this caching
If you are using a direct TCP connection and HTTPConnection, then you'll have to invent caching.
You might just store the response content and the URL in a hash table. The URL would be the key, the text from the response would be the data object. Youwould then consult the cache (your hash table) prior to calling the URL over the conneciton. If the URL is already in the cache, you'll load the data from the table instead of over the connection.
I've done this strategy for downloading images: no point in downloading the same image over and over. Once in the cache, we get it from there.