The Vasari Pulse Gun Defense static structure currently has a "virtual_supply_cost" of 50 (equivalent to the threat level of a capital ship). I believe this to be a bug, as all similar static defense structures (including the low- and high-pierce turrets as well as hangars) for all races are valued at 10.

Background info for any uninitiated readers: all ships or structures either have an actual supply cost (ships), or a virtual one (strike craft, starbases, structures, or temporary spawned "ships" such as the TEC carrier's missile battery). My understanding (as a modder and not a Stardock dev, although I have also tested it to confirm) is that this value affects the AI's decision making when calculating the threat level in a gravity well and determining whether or not to attack/retreat, as well as for interface things like the size of the bars on the sides of planets and determining which audio voice lines to use (between the stressed/normal/overconfident versions).

The practical impact of this is that the AI will tend to avoid attacking Vasari planets with just a few of that specific defense structure built, as the AI views them as a much larger threat than they should.