Painfully Slow Web Browsing

[#1]

Last night and again in the last hour I've been suffering painfully slow Web browsing. This morning (between about 07:00 and 09:00) it was ok. Web pages are taking minutes to load (if they load at all). I'm assuming that there can't be a widespread problem or others would be reporting it here.
My sync sped is normal and I've just run a speed test which is also fine. I've also tried rebooting my router and de-installing the recent IE security patch (KB960714) as my problems seemed to start after I had installed this. Neither of these things have made any difference.
If I connect my works laptop wirelessly then everything is fine (using a VPN). My normal PC (the one on which I'm having problems) is wired to the router.
Now I'm stumped - any ideas please?
Bob

[#2]

Just to add to this, some sites (for example this one) are fine. Examples of ones that take ages to load are
www.paypal.co.uk
www.bbc.co.uk
www.microsoft.com

Bob

[#3]

Those sites work OK for me. You could try reducing the MTU to (say) 1400 on your wired PC; at one time the Microsoft site (in particular) was problematical for some users with larger MTUs, though I never had problems with the default MTU=1500. Are BT in the process of changing anything at your exchange to ready it for 21CN? (That's a rhetorical question, I'm not sure how you would know.)
Last night's problems with Plusnet websites were due to a caching DNS misbehaving, fixed round about midnight. Your assumption that a repeat of this problem would have been noticed by other users is a fair one to make.
David

[#4]

Hi spraxyt and thanks for the reply.
I'm a but nervous of changing MTU - I've never touched this setting in years and not had any problems before. My router is saying that MTU is set to 1458 by the way.
My exchange is green (it took 5 minutes for me to get on to the exchange checker site).
I've just tried pinging www.bbc.co.uk and am getting request timed out.
A tracert gives:
C:\Documents and Settings\Owner>tracert www.bbc.co.uk
Tracing route to www.bbc.net.uk [212.58.253.67]
over a maximum of 30 hops:
  1    <1 ms    <1 ms    <1 ms  www.routerlogin.com [***.***.0.1]
  2    20 ms    16 ms    18 ms  lo0-plusnet.pcl-ag01.plus.net [195.166.128.27]
  3    15 ms    16 ms    17 ms  gi1-2-803.pcl-gw1.plus.net [84.92.5.57]
  4    19 ms    20 ms    16 ms  te2-1.pcl-gw02.plus.net [212.159.1.114]
  5  154 ms    55 ms    17 ms  te2-2.thn-gw2.plus.net [212.159.0.190]
  6    16 ms    15 ms    15 ms  rt0.thdo.bbc.co.uk [212.58.239.25]
  7    16 ms    16 ms    16 ms  212.58.238.133
  8    16 ms    17 ms    17 ms  te12-1.hsw0.cwwtf.bbc.co.uk [212.58.239.222]
  9    *        *        *    Request timed out.
10    *        *        *    Request timed out.
11    *        *        *    Request timed out.
12    *        *        *    Request timed out.
13    *        *        *    Request timed out.
14    *        *        *    Request timed out.
15    *        *        *    Request timed out.
16  ^C
A tracert to www.plus.net gives:
C:\Documents and Settings\Owner>tracert www.plus.net
Tracing route to portal.plus.net [212.159.8.2]
over a maximum of 30 hops:
  1    <1 ms    <1 ms    <1 ms  www.routerlogin.com [***.***.0.1]
  2    19 ms    28 ms    18 ms  lo0-plusnet.pcl-ag01.plus.net [195.166.128.27]
  3    17 ms    17 ms    16 ms  gi1-2-803.pcl-gw1.plus.net [84.92.5.57]
  4    16 ms    18 ms    17 ms  te2-2.pte-gw1.plus.net [212.159.0.186]
  5    24 ms    16 ms    18 ms  te2-4.pte-gw2.plus.net [212.159.1.102]
  6    20 ms    16 ms    22 ms  ae0-102.ptn-gw02.plus.net [212.159.1.105]
  7    19 ms    20 ms    21 ms  gi0-1-31.ptc-gw1.plus.net [195.166.129.3]
  8    26 ms    23 ms    26 ms  pos1-0.pih-cr1.plus.net [195.166.129.250]
  9    26 ms    26 ms    28 ms  vlan8.pih-gw4.plus.net [212.159.0.30]
10    26 ms    28 ms    25 ms  if25.pih-lb04.plus.net [212.159.0.18]
11    27 ms    26 ms    68 ms  portal.plus.net [212.159.8.2]
Trace complete.
Does any of this help?
Bob

[#5]

I'd be interested to see  what would happen if you changed your dns server settings  (within windows, assuming that is what you're using) to point at the OpenDNS ones (208.67.222.222 & 208.67.220.220)
otherwise i might try rebooting my router (assuming that's what you're using too)

[#6]

I've already tried rebooting my router. I'm not sure how to change my DNS servers (yes I am using Windows - XP SP3).
Thanks both for your help but I've had enough for today - this has already taken up way too much of my time. In good optimistic fashion, I'll switch off and hope it's all ok by tomorrow !!! 
Bob

[#7]

Unless you've previously altered it the MTU on your PC is likely to be 1500, and having this larger than the router MTU is not recommended. Since you are unfamiliar with changing MTU on your PC have you ever changed its RWIN - usually they are both set using the same tool? The XP default for RWIN (usually 17520) is far too small for efficient packet transfer.
Before changing anything I suggest running a tweak test at DSLreports. To get the results set Service to dsl, enter 8000 for Download Speed, set Operating System to winXP (in your case), and leave Connection as normal. Please post the results URL you will find in small letters just above the red Do Not Copy/Paste the Page text.
Also download DrTCP from the site. I suggest picking the ".exe" version, it's only 52.5KB. Double-click the downloaded file to run it, it's a self-contained executable that doesn't install on your computer. If you ensure the Adapter Settings drop-down shows the correct adapter (you might only have one) the MTU value will be shown in the right-hand box (blank means 1500).
David

[#8]

Well, I've been on-line for about half an hour this morning and so far everything appears to be back to normal. However it was ok yesterday morning and slowed down in the afternoon so I'll try again later in the day.
David, I've run the tweak test and the url is http://www.dslreports.com/tweakr/block:afde99?service=dsl&speed=8000&os=winXP&via=normal
I've run DrTCP and attached a screenshot of the result. I'm getting a bit out of my depth here and I'm not sure what my adapter settings are. I left it as the default which was Ethernet Adapter. I am using Ethernet to my router.
Thanks again for your help.
Bob

[#9]

Logged on again at 11:00 and everything still seems to be ok. I guess I'll have to put it down to just one of those unexplained things.
I've had a read around about MTU and RWIN and have changed my router MTU to 1500 and my RWIN to 130456. The tweak test is now giving http://www.dslreports.com/tweakr/block:2fc92a0?service=dsl&speed=8000&os=winXP&via=normal so I appear to have optimised these settings. I ran a before and after speedtest with no discernable difference but hopefully I've not made it any worse.
Thanks to David for you help on this.
Bob

[#10]

Hi Bob,
Well done, you've made the changes I was about to suggest (I was going to suggest RWIN=128480 which is the value I use, but anything around that value is fine).
The data transfer on the original setting is a little smoother, but idle time has been reduced slightly with the latter. Sort of swings and roundabouts. I suggest seeing how things go with these settings. It's likely that outgoing packets could have been fragmented with the previous setting which might have caused the problems you experienced - time will tell.
If you do a speedtest now is the download speed a little faster?
David

[#11]

Quote from: spraxyt

If you do a speedtest now is the download speed a little faster?

Speedtest results are about the same as before.
Bob

[#12]

Thanks for that feedback. I would be interested to hear whether you experience the slowdowns any more after trying the new settings into the New Year.
David