There is a way to have a session to yourself for at least a little while. One person disconnects his internet for a moment and ends up in a solo session, he then invites everyone to a mission and you will all be in that session with no other players, if you can get two groups as rivals (even if you aren't fighting each other) you will have less NPC's to contend with in those missions.
Windows 10 Pro Gigabyte 970A DS3P FX AMD FX6300 Vishera 3.5 Ghz ASUS STRIX GeForce GTX 970 Overclocked 4 GB DDR5 16Gb Patriot Viper 3 RAM DDR3 1866Mhz Onikuma Gaming Headset (has annoying blue lights I don't use)