I think Ive found a fix for some of the lag in-game.
The trade was hanging all the time and the refresh took ages. So I disabled the hardware acceleration tab - this has certainly fixed the trade refresh lag for me, and it appears other elements have improved this morning since I did this.
So for those of you interested, its as simple as this:
Right-click the screen whilst in the game.
Select Settings...
untick the hardware acceleration box
That's it, all done.
Once you have finished playing the game, you will probably need to switch the accelerator back on for Youtube vids etc..
Any comments welcome