A common complaint about DCCs is their lack of speed. mIRC's default DCC options leave the speed at a pathetically low level; to speed things up, try the following commands:

• /dcc packetsize 4096
• /fsend on
• /pdcc 999999999

The first command tells mIRC to send files in 4096 byte packets, the largest possible, and usually the most efficient. (if you are on a slow or noisy connection, you may find a smaller number provides better results.)

The second command tells mIRC to send data without waiting for the other end of the connection to acknowledge the received data. This means packets get sent in groups or streams instead of one at a time, and usually greatly speeds things up.

The third command tells mIRC how much to 'pump' the DCC, which affects how well the fast send (the above option) works. This simply puts it at a really high rate.

Once these options are set, they should stay set unless you reinstall mIRC.

[via mirc.net]