Adding large torrent slowsdown downloads

[Jerico]

As the topic says when I add a torrent, let's say around 40 Gigabytes(don't know what the "border" size is when this starts to happen), all of my current torrents slowdown to a few kilobytes a second all the way to halting their transfers completely. Is there away around this? Running W7-64bit/qBittorrent 4.1.2-64bit. The harddrive is standard 6TB Seagate.

EDIT: The harddrive is connect through a control card so could this be the cause of the problem?

[Switeck]

Yes, sadly allocating files for a new torrent tends to bring everything else to a halt.

Are you using full allocation, sparse, or something other for the files?

[Jerico]

[quote="Switeck"]
Yes, sadly allocating files for a new torrent tends to bring everything else to a halt.

Are you using full allocation, sparse, or something other for the files?
[/quote]
Full(default) I guess since I haven't changed anything conserning allocation, and the drive is formated as NTFS.

[Switeck]

Full allocation is exactly what it says -- fully allocating the entire files before downloading anything.

Sparse would be marginally better if it wasn't insane in how it works -- file fragmentation with that mode is crazy-high, which can cause horribly slow read/write speeds on the HDD.

Defragging a HDD after maybe each 100 GB downloaded can help slightly no matter what method is used.