Slow navigation when logged

Hi everyone:

When I navigate in my site staying logged, the site turns slow, very slow to open each page (10 to 18 seconds) but when I am not logged, the pages open in 1 or 2 seconds. This happen in IExplorer 8 like in Firefox 3.6

I have disabled all the plugins, but nothing. So, I thought.: There is any way to stay logged-in in one browser window and logged-out in other browser session? So this way I would be to navigate fast in the not logged session. May be someone knows any plugin to do that?

Thank you and I hope anybody may help to me.