Why's SD -> Ethernet Card -> Webbrowser so slow?

Without it, it may not send the last packet. There may have been less than 64 bytes in clientBuf.

Good point, I went and added it back like below. Next project is to get all the file uploading into a single function.

          if (myFile) {

            byte clientBuf[64];
            int clientCount = 0;

            while(myFile.available())
            {
              clientBuf[clientCount] = myFile.read();
              clientCount++;

              if(clientCount > 63)
              {
                // Serial.println("Packet");
                client.write(clientBuf,64);
                clientCount = 0;
              }
            }
            //final <64 byte cleanup packet
            if(clientCount > 0) client.write(clientBuf,clientCount);            
            // close the file:
            myFile.close();
          }