on 01-08-2012 12:09
You can download this through Kies, although I can't vouch for O2 as I don't have that firmware anymore. It has around four-hundred fixes including the lag between tasks when multitasking. Alledgely so, anyway.
on 01-08-2012 14:08
After the installation I did notice a couple of bugs, such as the serial number of some hardware marked as 0's only. Although it did seem a bit quicker, I reverted back to 4.0.3 in the meanwhiile till I get some more feedback about this.