Error:
Exception ticking Bullet_PSeven77267 (at (0, 0, 0)): System.NullReferenceException: Object reference not set to an instance of an object
at CombatExtended.Compatibility.VanillaFurnitureExpandedShields.ShieldInterceptsProjectile (Verse.Building building, CombatExtended.ProjectileCE projectile, Verse.Thing launcher) [0x0003e] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at CombatExtended.Compatibility.VanillaFurnitureExpandedShields.CheckCollision (CombatExtended.ProjectileCE projectile, Verse.IntVec3 cell, Verse.Thing launcher) [0x00057] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at (wrapper delegate-invoke) System.Func`4[CombatExtended.ProjectileCE,Verse.IntVec3,Verse.Thing,System.Boolean].invoke_TResult_T1_T2_T3(CombatExtended.ProjectileCE,Verse.IntVec3,Verse.Thing)
at CombatExtended.Compatibility.BlockerRegistry.CheckCellForCollisionCallback (CombatExtended.ProjectileCE projectile, Verse.IntVec3 cell, Verse.Thing launcher) [0x00029] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at CombatExtended.ProjectileCE.CheckCellForCollision (Verse.IntVec3 cell) [0x0000e] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at CombatExtended.ProjectileCE.CheckForCollisionBetween () [0x0014a] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at CombatExtended.ProjectileCE.Tick () [0x0006b] in <ee67a7b42cfc42cb9f1618d5b5e78d9c>:0
at (wrapper dynamic-method) Verse.TickList.Verse.TickList.Tick_Patch1(Verse.TickList)

Starts when the shield is activated and continues indefinitely (even if you remove the reason for its activation, for example, kill all raders). With one shield 10 tps is lost. With multiple shields drops to 0-1 tps. The error disappears after disconnecting all shields from electricity or destroying them. It looks like the type of bullet is random.