My quad core i5-3550@3.3GHz converting a dvd-clip with no extra filters clocks in at 3-3.5fps. LinuxMint 64-bit.
Adding my HTPC as an extra encoding server converts the same clip at 5-6fps. It runs adual core i3-2100@3.1GHz with HT, so 4 threads. Win7 64-bit.
This seems to suggest that HT helps with DVD-o-matic. But I'm not certain. Is it better to run your CPU with HT off and use only 2 threads, vs having HT on running 4 threads. My gcc-compiles at work do not care for HT.
Encoding servers works REALLY well!
An idea: take a specific clip with certain settings and run a benchmark to get conversion-times that are comparable. The clip you use in the manual maybe? This might be good to learn what HW is best for the money.
I will do some tests on the 2 machines at Zita and get back. Nothing really fancy, but quad core intel and amd. Not this week though.