How to fix extremely slow render in AE CS6?

Hi,

we've just upgraded from CS4 to CS6.

A composition that used to need 9 minutes to render, needs 2 hours now.

AE is updated and we don´t use the option "Render Multiple Frame Simultaneosly"

We've tried to delete different layers from the composition and the only way to improve rendering time is deleting wiggle expressions. Even if we transform these expressions to keyframes, the render lasts hours.

We need our wiggle expressions, how can we solve this problem?

Thank you very much!