is there anything fast first pass and slow first pass?

[pandy]

So do you know what defaults ffmpeg x265 uses for 1st pass?
Am a bit more intrested in ffmpeg x265

Use same settings as you intend to use in 2-nd pass - it is quite obvious that 1-st pass analyze video and 2-nd pass use same coding techniques only to allocate available "bits" better - ideally you should use same settings - fast 1-st pass use some tricks to speedup overall encoding time but if you don't mind to wait then use same settings as for 2-nd pass.