[Zope-CMF] Tale of Four Web Sites

[BOB.BARTER at sbcglobal.net]

I hope this post is not too long.  I have two questions that I
will elaborate on below:
1) why is my Plone site's initial download so large?
2) why does my browser make effective use of its cache for my
site and not for three other sites that I have tested?

I have been having performance problems with a Plone site that I
am developing, so I decided to compare my site with three other
Plone sites.  I suspected server problems, so the first thing I
did was a Google search where I found a couple of
recommendations.  I increased the “Target number of objects in
memory per cache” to 8000 as recommended, but it did not seem to
make much of a difference.

I decided to look at the bandwidth used and total bytes
downloaded for my site plus three other sites.

I'm limited to about a 15 Kbyte/sec bandwidth on my IDSN line. 
The bandwidth seemed consistent for all four sites.

On the client side I saw a dramatic difference in the way my site
came across the net compared to the other three sites.  For
roughly comparable sites (always a bad assumption), my site had
an initial download (after clearing the browser cache), two to
three times as large as the other sites.  Subsequent downloads
for my site were then one half to one third the size of the other
sites (for their subsequent downloads).

Site 1: 56Kbytes, two tabs, left column only, one small logo,
cleanest of the four sites
Site 2: 93Kbytes, no tabs, right and left columns, three medium
sized images, most complicated
Site 3: 70Kbytes, six tabs, one banner add, one logo, left column
only
Site 4: 170Kbytes, three tabs, left and right columns, one logo,
close to “out of the box”, my site.

Client side:
Win/xp laptop
IE6.0, cache checking: “Automatically”(whatever that means)

Site 4 (my site):
Linux (do not know details)
Zope 2.6.2
CMF 1.4.2
Plone 2.0-RC3

Using the networking monitor that is part of the Task Manager in
Win/xp, reset the Bytes Received counter, start IE, clear IE
cache of files and cookies, connect to target site, record
bandwidth utilized and Bytes Received (after page has loaded),
close IE, reopen IE, do not clear cache, reset Bytes Received
counter, connect to target site, record bandwidth and total bytes
as before.  Repeat without clearing cache.  Go to next site and
repeat.

Results:
Bandwidth utilized-- hard to judge, but no obvious differences.

Bytes Received (view with mono-spaced font):
Site  Initial download  Subsequent downloads
 1      56,198            55,406    55,417
 1      55,417            55,417    55,417

 2      92,000            94,976    93,476
 2      93,492            93,492    93,492

 3      74,660            67,747    63,171
 3      68,073            73,501    74,885

 4     169,855            32,156    32,212
 4     169,755            32,205    32,245
 4     169,755            32,156    32,156

Is there a way to turn off client side caching from the server
and could the first three sites be doing that?

Is it possible that Plone 2.0-RC3 is more verbose?

Any other suggestions?