Web Surfing Through Treacle

[#1]

I've been seeing very high latency for ordinary web browsing lately.
Just as if the Internet had been converted from a cat-based infrastructure to a treacle-based one   
Not that I don't like treacle, but it has no valid place in the HTTP standard.
As usual chez PlusNet, nothing to point at metric-wise. ICMP latency is 5-6ms, speedtest OK (except I still don't understand why the upstream continues to hover around 15Mbps when it should be almost 20). DNS not an issue.
But the reality is web surfing is rubbish.
There is a get out of jail free opportunity with upcoming line rental increases.
I could pay £15 extra a month and move to AAISP without penalty.
Of course, if the problem is the BRAS it may not help.
But I have no way of knowing what the problem is.
I think it's PlusNet's network. But I'd have to commit to a significantly more expensive service to find out...
What to do, what to do...   

[#2]

Hi  InterZoom,
Can your replicate this problem across different devices?
Also let me know what a speed test over ethernet shows you: http://speedtest.btwholesale.com/
Incidentally I've just run a fresh set of diagnostics which didn't hint towards any issues.

[#3]

Hi Adam,
Thanks for the interest.
Yes, there isn't a difference between desktop, laptop and smartphone, for example.
In fact, the experience has been much the same as the web browsing latency you often get on a 3G mobile, where the connection is kept going using buffering which would be wildly excessive for a fixed line connection: hence my supposition that PlusNet's traffic queuing may be the cause. And my repetition of the suggestion made by PlusNet staff in the past that the BRAS may be another possible source of delay.
I note that a discussion over at the ThinkBroadband Forums seems to echo the same observation, with both RobertoS and Chrysalis finding web browsing subjectively "snappier" when they moved to AAISP and Sky respectively, despite no significant change in speed test results.
http://speedtest.btwholesale.com/ ;   gave me this just now:
--------------------------------------------------

Download speed achieved during the test was - 38.96 Mbps
For your connection, the acceptable range of speeds is 60 Mbps-77.35 Mbps .
Additional Information:
IP Profile for your line is - 77.35 Mbps

Upload speed achieved during the test was - 13.88Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

--------------------------------------------------
But aside from that unexplained low upstream result (which the TBB test shows as well, and has done for some time,) I'm afraid I can't point to any specific number to confirm the impression of laggy web browsing, and it doesn't surprise me that your standard diagnostics haven't turned up anything either.
I suspect that if I do migrate away, the issue will go away. But if you're going to point the finger at BT Wholesale(?) then that might not be the case; unless I were to move to Sky, presumably.

[#4]

I get exactly the same slow browsing on my connection too. Its the same on three laptops and two smart phones. A mixture of apple, android and windows operating systems.
Some times it is so useless I just turn wifi off and use a 4G connection which seems much faster.
Only seems to happen in evenings so I am wondering if it is contention on my cabinet. Any plusnet staff able to check my account for anything obvious?
Connecting the devices to a my neighbours BT connection via their home hub sees a marked improvement which I guess makes contention less likely?