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You can try using the "Show / Hide" function of the "Conditions".
You can learn more about the Conditional logic by using this guide: http://www.jotform.com/help/57-Smart-Forms-Using-Conditional-Logic.
Also, as I mentioned on the other thread, the form lags, not only because it is quite long but because there are problems with the theme or styling that you have.
Here's a sample form that I did for the show and hide function: http://form.jotformpro.com/form/50981789493979. Here are my steps.
1. Click the "Conditions" option in your form builder.
2. Choose the "Show / Hide a form field".
3. Setup your rules and actions. In my case, I used "Show Multiple", please do take note that you don't need to use "Hide" if you are already using the "Show" action, this is because when the condition is not met it automatically hides the fields.
I hope this helps.