To avoid water hammer as well as damage to your plumbing (including your indoor plumbing, not just the irrigation system), you don't want water to travel through pipes at a speed faster then 5 feet per second. A 3/4" copper line will reach speeds of 5fps at flows around 7GPM.
Now at my house, I have 1' PVC between the meter and the house (it transitions to 3/4" copper a few feet before the line enters the house). But even if you also have a 1" PVC line to tap into, you're still limited to about 11 GPM through the 1" line.