Just another ANNOYING problem with internet

Question

Hello everybody !
So here we go, I am another user that has problems viewing web pages. To make a long story short I would like to add that though I am not a system administrator by any means, I am an experienced user. So if I say for example "I did nothing but the program stoped working correctly" DOES realy mean that I did nothing at all (therefore it doesnt mean that I occasionaly pushed few buttons while viewing complex settings and then forgot about it).
PROBLEM : Sometimes (randomly) I am not able to view web pages. The problem may disappear suddenly, but otherwise I have to reboot computer to solve the problem (untill it happens again. And it WILL happen withing ~30min...4 hours, so several times a day)
I USE : Macbook air 2012 (i7 8gb if it does matter). MacOS 10.8.2.   Everything is up to date, I frequently check the system for updates.
WHAT HAVE I TRIED TO DO TO SOLVE THE PROBLEM :
1) I have changed the wireless channel so that nobody around uses the same one
2) I have changed router and internet provider (well I did not change them, I just use my mba at office, at home and somewhere else. Each place has its own router (d-link at work and apple airport express at home) and its own provider)
3) I have changed mtu (maximum transmission unit) to 1453 from 1500 by default (System preferences -> network -> advanced )
4) I have tried different public DNS servers
5) I did try to request DHCP once again when the problem appears
6) The last but not least - I have tried different browsers (safari, opera, firefox)
The only thing that works yet - reboot.
MY STUPID THOUGHTS ON THAT :
- This is not a router problem, because I have already tried about 4-5 different models, including D-link, Airport and Asus
- This is not an internet connection problem generaly (I am able to use skype, teamviewer etc. while the problem occurs)
- This is not a macbook problem, because if I boot Windows (via bootcamp), it seems like I do not face that problem at all
As a result : this is a MacOS problem, and I have to look for fix inside it.
SOME ADDITIONAL INFO :
It realy happens suddenly: I am browsing webpages, everything is ok. Then bum - and the next page starts to load SLOWLY. Few more pages load SLOWLY (if there are pictures, I find "?" instead of them). And then pages stop loading at some moment. If I try to refresh the page, it might help sometimes. But then, finaly, I just lose opportunity to load web pages by any means.  
The problem may go away for some time, but it will return for sure. Rebooting every time is incomfortable for me, since I have a lot of stuff opened and rearranged between different spaces (desktops).
Thank you for your time in advance guys ! Hope some of you have already faced the problem and have found the solution.
Thank you for your time guys.

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It won’t solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
Third-party system modifications are a common cause of usability problems. By a “system modification,” I mean software that affects the operation of other software — potentially for the worse. The following procedure will help identify which such modifications you've installed. Don’t be alarmed by the complexity of these instructions — they’re easy to carry out and won’t change anything on your Mac. 
These steps are to be taken while booted in “normal” mode, not in safe mode. If you’re now running in safe mode, reboot as usual before continuing. 
Below are instructions to enter some UNIX shell commands. The commands are harmless, but they must be entered exactly as given in order to work. If you have doubts about the safety of the procedure suggested here, search this site for other discussions in which it’s been followed without any report of ill effects. 
Some of the commands will line-wrap or scroll in your browser, but each one is really just a single line, all of which must be selected. You can accomplish this easily by triple-clicking anywhere in the line. The whole line will highlight, and you can then either copy or drag it. The headings “Step 1” and so on are not part of the commands. 
Note: If you have more than one user account, Step 2 must be taken as an administrator. Ordinarily that would be the user created automatically when you booted the system for the first time. The other steps should be taken as the user who has the problem, if different. Most personal Macs have only one user, and in that case this paragraph doesn’t apply. 
Launch the Terminal application in any of the following ways: 
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.) 
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens. 
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid. 
When you launch Terminal, a text window will open with a line already in it, ending either in a dollar sign (“$”) or a percent sign (“%”). If you get the percent sign, enter “sh” and press return. You should then get a new line ending in a dollar sign. 
Step 1 
Copy or drag — do not type — the line below into the Terminal window, then press return:
kextstat -kl | awk '!/com\.apple/{printf "%s %s\n", $6, $7}' 
Post the lines of output (if any) that appear below what you just entered (the text, please, not a screenshot.) You can omit the final line ending in “$”. 
Step 2 
Repeat with this line:
sudo launchctl list | sed 1d | awk '!/0x|com\.(apple|openssh|vix)|edu\.mit|org\.(amavis|apache|cups|isc|ntp|postfix|x)/{print $3}' 
This time, you'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. You don't need to post the warning. 
Note: If you don’t have a login password, you’ll need to set one before taking this step. If that’s not possible, skip to the next step. 
Step 3
launchctl list | sed 1d | awk '!/0x|com\.apple|edu\.mit|org\.(x|openbsd)/{print $3}' 
Step 4
ls -1A /e*/mach* {,/}L*/{Ad,Compon,Ex,Fram,In,Keyb,La,Mail/Bu,P*P,Priv,Qu,Scripti,Servi,Spo,Sta}* L*/Fonts 2> /dev/null  
Important: If you formerly synchronized with a MobileMe account, your me.com email address may appear in the output of the above command. If so, anonymize it before posting. 
Step 5
osascript -e 'tell application "System Events" to get name of every login item' 2> /dev/null 
Remember, steps 1-5 are all drag-and-drop or copy-and-paste, whichever you prefer — no typing, except your password. Also remember to post the output. 
You can then quit Terminal.