A question about packets on a web server...
 

I'm running Slackware 12.0 and I have an apache web server up. I've been using tcpdump dst port 80.

Then I got to another computer and bring up the hosted web page. A few get packets go by. Then, when I click on a link to download a file, the firefox open, save box pops up. While the box is open, tcpdump dst port 80 runs like crazy. Tons of packets going in until I click open save or cancel. What is the purpose for that flood of packets? I mean, that's not very efficient when it comes to network traffic.

Caveat: This is just me speculating. No real facts here.

I've long suspected that firefox actually starts downloading a file that you select before you tell it to. That way it appears to be downloading faster than it really is. IMO, the packets you're seeing help support this hypothesis.