Any chance you could make the activation delay configurable? Above and beyond would be configurable per turret, but even a single global setting for all turrets would also make a big difference.

Had the same suggestion. I dug into the source and saw you can set the turret delay via a console command, e.g.:

/c remote.call("Turret_Delay", "set_delay_time", 30)

there are other calls, too, such as excluding/including a surface:

/c remote.call("Turret_Delay", "remove_excluded_surface", game.player.surface.name) 
/c remote.call("Turret_Delay", "add_excluded_surface", game.player.surface.name)