Slow ftp transfer using php over pptp in linux

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http://serverfault.com – We have a remote ftp server setup in a geographically different network accessable from our network with VPN (PPTP). The VPN connection is limited to 4Mbit/s. We are downloading a specific file every day that is constantly increasing in size, but is currently at around 5 GB. When transferring files on my local terminal using FileZilla on a Windows platform, files always gets downloaded at maximum speed (4Mbit/s) and finishes in just over 3 hours. When downloading from a php script using ftp_get() on a linux server, the transfer is much slower and takes around 10 hours to finish. The transfer (HowTos)