iRule send CPU utilization to 100%

As I mentioned the irule works now. However, we are noticing very inconsistent results from the different clients hitting the website. Some people get the "system down" page, others just get a spinning circle as firefox tries to load the site. We tried firefox, chrome and ie. We cleared the cache and cookies for each browser. What we found is that IE works 100% of the time. Firefox and Chrome don't work. Eventually after about 10 minutes, all the browsers get the systemdown page, but only IE works right away. I tried disabling persistence to see if that helps, but it did not. Any idea why the browsers would behave this way?