Very slow downloads

[wirehack7]

Hello community,

Subsonic runs at it's own dedicated server:
CPU~Quad core Intel Core i7 920 (-HT-MCP-) clocked at 1600 Mhz Kernel~3.2.0-4-amd64 x86_64 Up~90 days Mem~1443.7/12038.8MB HDD~3000.6GB(42.7% used)

Also it is running a Apache reverse proxy, streaming is running smooth, also I did open 4040. The server has an uplink of 1GBit/s

When I want to download a big file, like around 8GB, the download is really slow. Only around 146KB/s

What could here be the problem? The rest of Subsonic runs smooth and not slow.