I played it on r1931 with following settings:
Ignore invalid memory access:ON
Ignore inmapped imports:ON
Use Media Engine:ON
Extract media files to tmp folder:OFF
Decode audio files with SonicStage:ON
and left General, Video and Audio options with default settings
So far I've beat the game 3 times on
Geass route (default route)
Kuro no Kishi-dan route and
Nippon Kaiho Sensen route (which is the whole reason to play this game as NKS route is exclusive to PSP version of Lost Colors)
The game runs at full speed most of the time. Sometimes it will start to randomly slow down or even freeze, but it's not that big of a problem since this game has an auto-save feature and everything works fine once you reset and reload.
Ignore invalid memory access:ON
Ignore inmapped imports:ON
Use Media Engine:ON
Extract media files to tmp folder:OFF
Decode audio files with SonicStage:ON
and left General, Video and Audio options with default settings
So far I've beat the game 3 times on
Geass route (default route)
Kuro no Kishi-dan route and
Nippon Kaiho Sensen route (which is the whole reason to play this game as NKS route is exclusive to PSP version of Lost Colors)
The game runs at full speed most of the time. Sometimes it will start to randomly slow down or even freeze, but it's not that big of a problem since this game has an auto-save feature and everything works fine once you reset and reload.