Extreme slowness with Airport after installing 10.5.5

Question

OK, I've been nailed by "sudden browser slowness", which, if you look at the number of Google hits in the past few days, seems to be a wide-spread problem. It began for me on evening (~7:00 PM CST) of September, 30th.
I'm running Version 10.5.5, and have been since the public release.
Like most others, I'm sure, I assumed that it was my ISP or router. I recycled both the modem and router, neither of which cured the problem. I cycled my MacBook Pro as well... no dice. The problem has been persistent and affects both Safari and FireFox (v3.0.3). I have a second MacBook Pro that I use for work, so I fired it up and hit my Wierless (D-Link); it was working correctly.
I managed to dig up an ethernet cable and jacked my "poorly performing" MBPro into the router... it was lighting fast. I belive there is an issue with the MBPro's AirPort card and the new 10.5.5 release.
My personal MBPro (the afflicted unit) is approximately 1 year older than my work MBPro, which works correctly on the same network/router.
I've ruled out viruses/malware and even switched router broadcast channels... and yes, even applied OpenDNS IP addresses.
My "afflicted" MBPro info:
Hardware Overview:
Model Name: MacBook Pro 15"
Model Identifier: MacBookPro2,2
Processor Name: Intel Core 2 Duo
Processor Speed: 2.33 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 3 GB
Bus Speed: 667 MHz
Boot ROM Version: MBP22.00A5.B07
SMC Version: 1.12f5
Serial Number: W870515KW0H
Sudden Motion Sensor:
State: Enabled
AirPort Card Information:
Wireless Card Type: AirPort Extreme (0x168C, 0x87)
Wireless Card Locale: USA
Wireless Card Firmware Version: 1.4.4
Current Wireless Network: AirPort is currently turned off
My "working" MBPro:
Hardware Overview:
Model Name: MacBook Pro
Model Identifier: MacBookPro4,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 4 GB
Bus Speed: 800 MHz
Boot ROM Version: MBP41.00C1.B00
SMC Version: 1.27f1
Serial Number: W881130FYJZ
Sudden Motion Sensor
State: Enabled
AirPort Card Information:
Wireless Card Type: AirPort Extreme (0x14E4, 0x8C)
Wireless Card Locale: USA
Wireless Card Firmware Version: Broadcom BCM43xx 1.0 (4.170.46.11)

Answer 1

Hi,
1) Everyone would see it
I don't believe everyone would see it; just those with a particular combination of items, say like the physical chipset used for the wifi (note that I have two MBPro's that where manufactured ~1 year apart and they have different AirPort specs) and any number of sub-components.
Additionally, the fact the 10.5.5 release was supposed to patch bugs relating to AirPort specific issues... issues that I have not experienced on either of my machines over the last 18 months, would indicate that is in fact possible for some people "see" problems that I don't "see". Therefore I must conclude that I or others might experience issues that yet another set do not seem to suffer.
2) Other things would be affected as well
Not necessarily. In fact:
1. Physically connecting the MBPro to the router via an ethernet cable, thereby taking the AirPort out of the path, and witnessing "spot on" normal performance in both browsers, would suggest that the problem isn't related to the bowsers, their plug-ins (or the OS in general).
2. I can uses my 'work' MBPro on the same wifi router side-by-side with 'personal' MBPro and do not experience any degradation in performance what so ever. This reduces (if not eliminates) the chances that my issue is with my wifi router (I even switched my routers broadcast channels to to every possible setting and the findings remained consistent across both machines).
Network hardware doesn't know the difference between DNS requests and any other traffic (HTTP >> requests, streaming movies, etc.)
I agree. I wasn't clear in my posting, but this was supposed to be a 'tongue-in-cheek' statement. I had seen numerous postings where this was a recommended solution, so I hoped to avoid getting that advice, by mentioning that I had done so. (I did it, just for the heck of it anyway... of course it didn't solve anything)
It could be someone nearby who just bought a Wi-Fi router that's suddenly interfering with yours, or a neighbor who bought a 2.4 GHz cordless phone or any number of other things.
Have you tried downloading iStumbler to check whether there are any new routers in your area that may be interfering with yours?
Good call... but I did verify that I'm not in proximity to any other wifi devices.
Further, the fact that it "just began" implies it's something in your architecture rather than a software issue per se.
Speaking as a software engineer with decades of experience, that problems "just begin" are sadly the norm, not the exception. Especially when you code to the metal. I could be something as simple as a property file that was cleaned out in a background process that was missed in testing or something more elusive, like hardware/software combinations that are impossible to mock in a testing environment and are only discovered once the product is "in the wild".
Knowing this, I have attempted to communicate my "discoveries" here and on other sites, to help speed along a solution.
All of that being said, I truly do appreciate your time and effort helping me with this issue. The best way to get these problems resolved is through open cooperation.