o, after figuring that out, and delving into the Advanced controls Networking pref pane and setting the MTU to 1492 (default was 1500), now browsing was much snappier.
1. Goto System Preferences > Network
2. Select Built-in Ethernet and click Configure..
3. Select the Ethernet tab, and then you will see the MTU settings which should be set at 1500 (Standard)
4. Click Custom and then enter the value - in this case 1492
If 1492 does not work for you, you can try lower settings.
Thanks, seems to do the trick. Haven't played with numbers - if anyone can give further advice on the definitived setting then please post - if not, will just stick with 1492, as suggested by Darren.