Program Half-open limit fix intend for changing maximum number of concurrent half-open outbound TCP connections (connection attempts) in system file tcpip.sys.
This limit is entered by company Microsoft trying to make slower virus spreading from infect computer and cut down opportunities of participation of a computer in DoS attacks.
First this limit was entered in SP2 for Windows XP and present at all new versions of Windows. Limit consists that the computer is not authorized to have more than 10 concurrent half-open outbound connections. At achievement of a limit new attempts of connections are put in turn.
Thus, speed of connection to other computers is actually limited.
This limit is especially critical for P2P programs (µTorrent, BitComet, eMule, P2P TV etc.) users. When the P2P program works, pages in a browser can be loaded extremely slowly. The delay before the beginning of opening can make some tens seconds irrespective of speed of your connection.
Half-open limit fix cleans this limit, that is increases the maximal limit of half-open connections. For the overwhelming majority of users there will be sufficient the limit equal 100.
You can get Windows Half-open limit fix (patch) from here.
Source : half-open.com