Well, I got a bit bored this afternoon & dug out the Efika for a bit of a play around.
Note that when I reverted back to 2.3 I completely wiped 2.4 .
Today I upgraded it from 2.3 to 2.4 just like last time, except this time it's working fine.
It would seem that there was something wrong with the way the last (troublesome) 2.4 install was working.
Anyway, it seems that everything is back to normal & 2.4 works great, so all that was needed was a reinstall.
I wonder what actually went wrong though...why would it have ate RAM like mad before, but after rinstallation it works fine? Quite odd really!
PZ.