Just moved to ISP PLUSNET and now loading web pages is dead slow

Question

Just moved to ISP PLUSNET and now loading web pages is dead slow.
Like loading google will sometimes take 30 seconds to 1 minute but it used to load in a fraction of a second on my previous ISP.
Sometimes a new URL will take over a minute so I hit Stop Loading This Page and then try again and sometimes it might load instantly, or if not, it might continue to just drag on again.
It's so frustrating it's like being back on dial-up connection - but worse.
It feels like PLUSNET have put something on my Mac to slow it down.
PLUSNET has a restriction on how much I can use per month, which my previous ISP did not have, but according to PLUSNET's usage checker I am nowhere near the max, ie, I am allowed 10GB per month but the checker is showing I have used less than 100 MB so far this month.
I wonder if the PLUSNET usage checker is slowing down my usage coz it's really noticeable that it has only started to run slow since I moved to PLUSNET.
When I run a broadband speed check it always shows the feed coming in at around 5500 kbps or so which should be OK.
PLUSNET told me to go through their test page and I got to the part where it says install a Virus checker and an Adware checker but I'm not sure which ones to use coz I heard some of those checkers are themselves plants that infect you with a virus or keystroke logger.
Also I have Block Pop UP Windows running on Safari but yesterday a window popped up so that blocker seems to have been compromised somehow.
I have 17GB available on my HD of a total of 38GB.
Can anyone help me with this problem please?

Answer 1

(First, if yours is an Intel Mac, check that Safari is not running in Rosetta, which is enough to slow it to a crawl. If you are running Snow Leopard, run Safari in 32 bit not 64 bit.)
Adding DNS codes to your Network Settings, should gives good results in terms of speed-up:
Open System Preferences/Network. Double click on your connection type, or select it in the drop-down menu. Click on TCP/IP and in the box marked 'DNS Servers' enter the following two numbers:
208.67.222.222
208.67.220.220
(An explanation of why that is both safe and a good idea can be read here: http://www.labnol.org/internet/tools/opendsn-what-is-opendns-why-required-2/2587 /
Open DNS also provides an anti-phishing feature: http://www.opendns.com/solutions/homenetwork/anti-phishing/ )
Wikipedia also has an interesting article about Open DNS:
http://en.wikipedia.org/wiki/OpenDNS
Whilst in System Preferences/Network you should also turn off 'IPv6' in your preference pane, as otherwise you may not get the full speed benefit (the DNS resolver will default to making SRV queries). If you want to know what IPv6 is:
This is Apple's guidance on iPv6:
http://docs.info.apple.com/article.html?path=Mac/10.5/en/8708.html
Click on Apply Now and close the window.
Restart Safari, and repair permissions.
If that didn't do it, then try this as well:
Empty Safari's cache (from the Safari menu), then close Safari.
Go to Home/Library/Safari and delete the following files:
form values
download.plist
Then go to Home/Library/Preferences and delete
com.apple.Safari.plist
Repair permissions (in Disk Utility).
Start up Safari again, and things should have improved.
More useful information here:
http://guides.macrumors.com/SpeedupSafari
Less likely, but possible, is that the slowness is caused by a Trojan such as the one called 'DNSChanger' or 'OSZ.RSPlug', which can alter the DNS settings of your network connection. This particular Trojan can be inadvertently installed if you have come across certain Quicktime movies where got a window stating that you have to download and install a particular codec in order to see the video.
If you have agreed to that installation, your system can be infected and your DNS settings altered, which results in your system using the wrong DNS servers, which can slow web surfing to a crawl.
This can be fixed by downloading and running a freeware utility called DNSChanger Removal Tool which you can download from here:
http://www.versiontracker.com/dyn/moreinfo/macosx/33696
Once you have run that utility you have to re-boot your Mac, then reset Safari, and re-enter your DNS settings in System Preferences/Network.