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Setting a limit of 100 threads is a good place to start. That will probably translate to about 1000 requests per second, and chances are your IO will be the limiting factor before you get to that many requests anyway.
Bruce explained the basic structure of an HTML page. So there are controls (HTML for browses, forms etc which can be called as you would call a browse) and snippets of HTML or NetWebSource procedures which just dump in the requested HTML and can not be called directly by the user.
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Popups will give you a very Windowsy (Bruce actually compared it more to CPD) experience. Not search engine friendly, however.
SPAs - single page applications
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