That's very likely to overload a computer's cpu and storage drives -- and when that happens, a massive stall is the least of what's likely to happen.

Even Serial ATA 3 Solid State Drives (SSDs) can only manage ~400 MB/sec due to SATA-3 limitations.
Try testing with a much slower max speed limit in qBitTorrent, like 100 MB/sec.
If it works, then maybe test faster speeds...or just stick with whatever seems to work for now.