Here is a collection of a few tips to optimize and increase the download throughput and speed of BitTorrent files as well as P2P file sharing programs such as Kazaa, Gnutella, Shareaza, eDonkey, eMule, etc in Windows Vista. Some of the tips might already be known.

1) If you are using a router from your ISP to connect to the internet, follow the below mentioned steps:

a) Open your router’s configuration page
b) Look for an option that says Port Range Forwarding, Port Range or Virtual Servers

Note: If you can’t find step a or b, check out the routers section of portforward.com for your specific model

c) Add ports ranging from 6881-6999 and make sure to select both TCP and UDP
d) Forward or map the above mentioned ports to the computer running the BitTorrent client

The ports for P2P programs are as follows:

# Gnutella (Shareaza)
TCP and UDP ports 6346

# eDonkey and Overnet clones
TCP and UDP ports 4661-4672

# Kazaa and other Fasttrack clones
TCP and UDP ports 1214

#Ares Galaxy
TCP port 32285.

# Winmx and Napster
TCP and UDP ports 6257

#eMule
TCP and UDP ports 4661-4672 and TCP ports 5555,4242, 3306, 2323, 6667, 7778

2) If your ISP throttles BitTorrent bandwidth, there are two solutions:

a) Use a free VPN service such as SecureIX

b) Use uncommon ports: A BitTorrent client normally associates the TCP port number 6881. However, if this port is busy for some reason, the client will instead try higher ports upto 6999. You can change the port that your BitTorrent client listens to ranging from 49152–65534 or an unassigned port between 1024–49151 by going to the configuration settings of the BitTorrent or the P2P file sharing client. Make sure to follow the steps listed in Step 1 to forward or map the ports to your computer from the router.

3) Configure your Anti Virus/Firewall software to allow TCP and UDP ports listed above

Symantec Firewall-
McAfee Firewall
Trend Micro Firewall
ZoneLabs
Windows Vista Firewall

Note: Some firewall allow you configure ports based on the executable file name

4) Do not use Force Start: Force Start is used for starting a torrent manually. This torrent will be out of order from the queue. using Force Start will spread out your upload capacity over too many upload slots - and your overall download speed will actually suffer.

5) For Windows Vista OS limitations:

a) Increase the maximum limit of half-open TCP/IP concurrent connections using klitetools batch file

b) Set the TCP Auto Tuning to Highly Restricted by typing instead of completely disabling it:

netsh interface tcp set global autotuninglevel=highlyrestricted

This settings allows the TCP/IP window to grow beyond its default value.

If it restricting TCP/IP auto tuning doesn’t help, try disabling it altogether by typing:

netsh int tcp set global autotuninglevel=disable

A reboot of the computer is required after changing this setting

6) After changing the registry key in the OS, increase the maximum number of connections in the BitTorrent/P2P software itself.

Related:

P2P client for Windows Vista- Shareaza
Bittorrent client for Windows Vista- µTorrent Beta