This is highly unlikely, as Alt.Binz will always max out your connection, all other things being equal, and this is the experience of 99.9% of users. Explain more carefully how you're working out the difference in speed. Give precise reported speeds in each client, being clear about the difference between Mbps and MB/s.
Otherwise, check your Log for errors, check number of connections, check Alt.Binz is excluded from AV and firewall interference, etc.