performance issue with PEAR:SOAP and big files

Using the PEAR SOAP, I am building a simple WS to receive a set of big files and store them servers side. Responses times are desastrous. Digging, it seems the problem comes from the time spend to transmit the request to the server (in the code involved is in the code \pear\SOAP\Transport\HTTP.php in the function &_sendHTTP(&$msg, $options) ( around lines 460). I don't see why it takes so much time just to send the envelop ? fputs to discard simpleWS :\temp\50kb.file 0.001936 0.579828 c:\temp\200kb.file 0.015302 0.602267 c:\temp\1mb.file 0.031756 1.214124 c:\temp\5mb.file 0.119197 20.067515 c:\temp\10mb.file 0.251415 76.082576 c:\temp\50mb.file 1.199493 forever c:\temp\100mb.file 2.357067 forever c:\temp\200mb.file 4.645161 forever The benchmark is done against the discard port and with a simple fputs (thanks to Ian Eure). Where is this overhead coming from ?