Dejan, I have experimenting all day long with all SW versions.
SW 3 and SW 4 are FAR MORE OPTIMIZED for my 42LB671V then SW 5! Far more! Menu pops out in less than 1 sec. Didn't know this until today, or let me put it differently - I forgot how fast and fluent this TV was before.
Beside this, I've never had issue with memory leak on this TV.
I'm back again to 04.45.25 and that my final sw until series 6 is out (if ever).
I'm not suggesting anyone to do the same, just bringing the info.