2.9.9C .. Adding to cart ... Slows as I add more products.

[John2400]

PhP. 5.4 , memory 128 .. Joomla 3.3.4 . VM 2.9.9c

I have noticed that my site works very well.. But as I add to the cart it slows as I add additional products.
Product 1 instantly, 5 seconds later , product two takes 3 seconds and product 3 often takes 10 seconds.

They all end up in the cart and payments all work quite well. When I confirm the cart all goes well.

The site installs and opens on all browsers instantly. I just note this if there is a small loop somewhere.