What extensions do you have installed? You could try disabling them one by one or all of them and gradually add to see if that cures your speed problem. If Firefox is ok then it points to a problem with Chrome.
The problem appears to have returned, and as I use Chrome mainly for the PCA website, I am beginning to wonder if the problem lies there?.
A typical example this morning, was the amount of 'work or connections' that seems to occur, while waiting for pages to open. On a few occasions there have been delays due to 'Resolving Proxy', then Google etc etc?.
It would appear that I will need to do further experimenting. Thought that those interested might like to have the latest update!.
I had a similar problem using Internet Explorer (latest and previous version) on this website, and I put that down to IE, as other problem reports about IE were being aired. Chrome seemed the most stable on this website, so I commenced using that on the PCA website. So another rethink perhaps!.
Although you maybe moving away from the idea of Site Advisor (SA) being the cause, you might like to consider an alternative for use with Chrome. I use an extension to Chrome called WOT (Web Of Trust). Seems to do the job, but have to say at times it does give widely differing results from SA. Who knows which is more correct!