WinSCP transfers from a game server causing lagging in game.

I've rented a game server and am doing my own backups using FTP, no compression. I have these backups running on a schedule and have discovered that when I am playing the game (ARK: Survival Evolved) I get rubberbanding and lagging in game during the backup. I have lowered the maximum transfer rate and moved the backups to a different machine in my (Gigabit) LAN but the problem still occurs. Is there a "nice" command I can send to the game server to try and lower the impact of the backup?