losing FPS at runtime

hi guys!

class Pot(DirectObject.DirectObject):
    def __init__(self, sPx, sPy, sPz, nodeName):
        self.pot = loader.loadModel('models/pot.egg')
        self.pot.setPos(sPx, sPy, sPz)
        self.potSphereNode = CollisionNode( nodeName+'Sphere' )
        self.potSphereNode.addSolid( CollisionSphere(0,0, 0.12, 0.18) )
        self.potCollider = self.pot.attachNewNode(self.potSphereNode)

        base.collisionTrav.addCollider( self.potCollider, base.collEvent )
        self.accept( nodeName+'Sphere-in-playerSphere', self.collisionIn )
        self.accept( nodeName+'Sphere-out-playerSphere', self.collisionOut )

while three pots are in the scene the program runs at 60fps, when no one are in the scene the program runs at 170fps.

When there aren’t base.collisionTrav and the handler events the program runs better at 170fps. What am I doing wrong in the class?

What’s the problem?