I'm also experiencing same problems like arkw52. This can't be hardware, I've done some testing, and CPU (i5), memory (8 Gb 1600) and disk are healthy and there is plenty of hardware power to experience such lag..
I have Logitech wireless keyboard and mouse but only in Opera i feel lag when typing, switching between tabs (only 12 tabs!), opening a new tab..
Why do you think Logitech keyboard is problem?