New Transmission add-on thread

Hey i have been useing Transmission for some time now without problems but when i try to download a big torrent it hangs and some times even crashes im useing Transmission 2.42 on a ReadyNas duo the file im trying to download is 3xxgb big and its only a part of it like 50gb what can i do to make it work?

My Settings:
{
"alt-speed-down": 50,
"alt-speed-enabled": false,
"alt-speed-time-begin": 540,
"alt-speed-time-day": 127,
"alt-speed-time-enabled": false,
"alt-speed-time-end": 1020,
"alt-speed-up": 50,
"bind-address-ipv4": "0.0.0.0",
"bind-address-ipv6": "::",
"blocklist-enabled": false,
"blocklist-url": "http://list.iblocklist.com/?list=bt_level1",
"cache-size-mb": 8,
"dht-enabled": true,
"download-dir": "/media/BitTorrent/",
"download-queue-enabled": true,
"download-queue-size": 5,
"encryption": 2,
"idle-seeding-limit": 30,
"idle-seeding-limit-enabled": false,
"incomplete-dir": "/c/media/BitTorrent/Incomplete",
"incomplete-dir-enabled": true,
"lazy-bitfield-enabled": true,
"lpd-enabled": true,
"max-peers-global": 120,
"message-level": 3,
"open-file-limit": 32,
"peer-congestion-algorithm": "",
"peer-limit-global": 100,
"peer-limit-per-torrent": 30,
"peer-port": 6881,
"peer-port-random-enabled": 0,
"peer-port-random-high": 65535,
"peer-port-random-low": 1024,
"peer-port-random-on-start": false,
"peer-socket-tos": "default",
"pex-enabled": true,
"port-forwarding-enabled": true,
"preallocation": 1,
"prefetch-enabled": 0,
"proxy": "",
"proxy-auth-enabled": false,
"proxy-auth-password": "",
"proxy-auth-username": "",
"proxy-enabled": false,
"proxy-port": 80,
"proxy-type": 0,
"queue-stalled-enabled": false,
"queue-stalled-minutes": 30,
"ratio-limit": 2,
"ratio-limit-enabled": false,
"rename-partial-files": true,
"rpc-authentication-required": true,
"rpc-bind-address": "0.0.0.0",
"rpc-enabled": true,
"rpc-password": "{d15b146a3063b3ade7d0fecaa9602218a327a8c8gOoal64v",
"rpc-port": 8181,
"rpc-url": "/transmission/",
"rpc-username": "admin",
"rpc-whitelist": "*",
"rpc-whitelist-enabled": true,
"scrape-paused-torrents-enabled": true,
"script-torrent-done-enabled": false,
"script-torrent-done-filename": "/c/addons-config/Transmission/email_alert",
"seed-queue-enabled": false,
"seed-queue-size": 5,
"speed-limit-down": 400,
"speed-limit-down-enabled": false,
"speed-limit-up": 20,
"speed-limit-up-enabled": false,
"start-added-torrents": true,
"trash-original-torrent-files": false,
"umask": 18,
"upload-slots-per-torrent": 3,
"utp-enabled": true,
"watch-dir": "/c/media/BitTorrent/sources/",
"watch-dir-enabled": 0
}