Reducing Calculations Solid Particle System updateparticles

I'm having some framerate issues (granted there are 240k vertices)...

Getting about 58 on Desktop... Drops to 15 Chrome on  Laptop and then 8 on Firefox on Laptop...

http://crab.strangled.net/

I think this is the issue -- I need a method of skipping calculations... I tried Jerome's suggestion of waiting to calculate every 3 frames but this causes a stutter...  Any suggestions welcome!

Thanks in advance!

  SPS.recycleParticle = function (particle) {

    if (particle.idx > particleCount) {
      particle.alive = false;
    }
    else {
      particle.alive = true;
    }
    if (!particle.alive) {
      if (particle.scale.y == 0) {
        return;
      }
      particle.scale.x = 0;
      particle.scale.y = 0;
      particle.scale.z = 0;
      particle.position.x = Math.random() * 6;
      particle.position.y = Math.random() * 6;
      particle.position.z = Math.random() * 6;
      return;
    }
    else {
      particle.position.x = Math.random() * 6;
      particle.position.y = Math.random() * 6;
      particle.position.z = Math.random() * 6;
      particle.velocity.x = (Math.random() - 0.5) * speed;
      particle.velocity.y = Math.random() * speed;
      particle.velocity.z = (Math.random() - 0.5) * speed;
      var scale = scaleValue - 3 * (Math.random());
      particle.scale.x = scale;
      particle.scale.y = scale;
      particle.scale.z = scale;
      particle.rotation.x = Math.seededRandom() * 3.5;
      particle.rotation.y = Math.seededRandom() * 3.5;
      particle.rotation.z = Math.seededRandom() * 3.5;
      particle.color.r = Math.random() * 0.6 + 0.5;
      particle.color.g = Math.random() * 0.6 + 0.5;
      particle.color.b = Math.random() * 0.6 + 0.5;
    }

  };