|Not likely. Once the firewall has done it's initial inspection on the incoming traffic and decided it is "allowed" then it stops looking at that data flow.|
Many things can affect download rate. If the server you're downloading from is busy, it's going to be slower than if it's not. If more and more people keep connecting to the same server and downloading, your download rate is going to get slower and slower.
Also, network congestion can affect download rates. If you download during peak usage times on the internet, it'll be slower than doing it during non-peak hours.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.