My systems:
core I3, 2GB Ram DDR3, ATI Radeon 5470.
The first times i'm play DMC4, It run between 45-55 FPS at 1280X720(High settings). After a time, I change some graphic options and the fps drop down to 10-13 and can't be back even when i return default. I search in some forum and found some ideals. I go to C:/User/AppData/Local/CAPCOM/DMC4 end edit SLI=ON to SLI=OFF in config.txt file and it word good. The FPS return around 45-55. Yesterday, this things happen again, and even when i edit the SLI again, the FPS just 10-13. I'm so sad, please help me....
P/s: sorry about my English, it's my 2rd languages :|