[deleted]

[Alexander]

[deleted]

[miseru99]

The extra threads settings depends mainly on how many physical cores your cpu has. Normally PCSX2 has 2 heavy threads GS and EE, with MTvu that's 3. Soo max should be amount of cores in your cpu-2 or -3 if using MTvu, meaning 2 / 1 with mtvu extra threads on quad core cpu as yours.
You can always try more, if the game is light on EE/VU, but don't expect much gain except in extra temp;P.

[Alexander]

[deleted]

[KrossX]

Just try them numbers one by one, it's a rather quick test. You will clearly see which number is the best for your system.