So you need as many threads as you're delivering parallel files ? That reminds me the late 90's when everyone started to discover how easy it was to deal with blocking I/O using threads until they discovered that threads are very slow since you have to suffer from context switches all the time. As a rule of thumb, you must never run more threads than you have CPU cores, or you'll get the taste of context switches.

And it's really hard to scale using a model requiring one thread per connection. You'll hardly stand one million concurrent connections this way, and this can definitely happen for large objects.