If you already have Custom Firmwares 3.80 m33 - 3.90 m33 installed on your PSP you may already noticed that some games like Tekken Dark Resurrection are lagging which can greatly affect your gaming. There’s a quick fix for that by changing your PSP’s game speed to 333mhz and using Sony NP9660 UMD Mode. The downside when you set the speed to 333mhz are it consumes more battery therefore the shorter the play time and the faster the PSP heats up.

Fatmsmod is a patch/fix that loads the fat memory stick driver of 3.71 in 3.80/3.90 to make memory stick reading work better. fatmsmod of 3.71 usually works better because it has a better cache system, and usually reads on bigger blocks. As noted from the readme file included in the patch it uses more kernel memory, and it is unknown if it will have any kind of secondary effect running this module in 3.80/3.90 The lags in np9660 no umd mode won’t probably be solved, as that is a different problem.

To install Fatmsmod Patch, follow these steps:

1. Download the files needed
   • Fastmsmod.prx
   • FatmsmodV2  
2. Connect your PSP to your PC via USB Mode
    
3. Copy fastmsmod.prx on your PSP’s root Directory
    
4. Extract FatmsmodV2.rar anywhere on your PC
   • you can use WinRAR to extract .rar files 
5. Copy the extracted folder “FATMSPATCH” on “\\PSP\GAME\ ” folder of your memory stick
   • e.g. X:\\PSP\GAME (where X is the drive of your memory stick) 
6. Exit USB Connection Mode
    
7. Be sure to check your game speed and set it to default speed and I suggest you use the M33 No UMD driver

NEW FATMSPatch for 4.01 M33