Firefox v20 has just become very slow.

[joe at actionline.com]

Until recently, Firefox had been working fairly well, but as of
today, it has become strangely slow to open.

Once open, it seems to work generally okay for most websites; but
the initial start-up now seems to take 10 to 15 seconds.

I had previously implemented most of the about:config changes that
various sites have suggested, and I just checked them and all seem
to be revised as previously recommended.

I checked 'top' and there are no processes taking unusual amounts of
time or processing.

Is Firefox now a victim of bloatware?  Or what could be the problem?

Strangely, once I have one Firefox session running, I can open a
second and third and those pop up in a couple seconds. It's just the
initial session that is unusually slow to open.