Large data sets? So you are saying that 512-byte packets with no windowing work better? Bill, have you measured this?
Time to download a 100mb file over HTTP and a 100mb interface: 20 seconds. Time to download a 100mb file over FTP and a 100mb interface: ~7 minutes.
And yes, that was FreeBSD with the old version openssl library that shipped with 6.3.
As someone who copies large network trace files around a bit, 100MB at 100mb, over what I presume is a local (low latency) link is barely a fair test. Many popular web servers choke on serving files >2GB or >4GB in size (Sigh). I'm in New Zealand. It's usually at least 150ms to anywhere, often 300ms, so I feel the pain of small window sizes in popular encryption programs very strongly. Transferring data over high speed research networks means receive windows of at least 2MB, usually more. When popular programs provide their own window of 64kB, things get very slow.