Fortigate 200d strange behavior

           Good day.

I have an Fortigate 300d which, block or make slower some unblocked web sites that contains javascript code. I've tried to make an account that can access all sites without restrictions. No anti-virus,no web filter, etc. Nothing restrictive. That sites (I found already 3 of them) doesn't display all pages correctly, or doesn't execute javascript code and browsers remain unresponsive.

I've tried from others Internet connections and those sites work very well. I have no clue what is happening.

    Thank you.