I am an old sheet metal fabricator and I would use some 18 inch bull dog cutting shears to cut the lashing wire with. They have about a 8-10 inch cutting blade on them and seemed to work a little faster than using the standard tin snips. Bulldog shears will run you around $ 60-$80 bucks for a good pair and when they get dull just bring them in and have them sharpend.
You can get some electrical shears that would knock the time in half, but I think they would be a little auckward to use.
just my 2 cents.