Gran Turismo PSP Emulation Issues

[WindowsMaster]

My computer ain't the greatest in the world, but for whatever reason, it can emulate PSP games pretty well.
Yep.
All except for Gran Turismo.
For some god-forsaken reason, I'm getting lag in the MENUS, and sometimes it can even affect the gameplay!
There are different results depending on a situation:
>Loading a race from the menu transfers the lag to the gameplay
>A race loaded from a save-state runs perfectly fine
>If a race is loaded from the menu, slowing down the car can slow down the framerate...for some reason


Here's my setup.

Computer: Lenovo G50
OS: Windows 7 Ultimate SP1, x64
Processor: AMD A6-6310 with Radeon R4 graphics
RAM: 4.00 GB

PPSSPP
No VSync
No postprocessing shader, I have to resort to D3D9 for Gran Turismo and only Gran Turismo
1x rendering resolution, again, only for Gran Turismo
1x window size...you get the idea
Buffered rendering
Frameskipping set to automatic if the framerate ever starts having a seizure
Texture filtering set to automatic
Screen scaling filter set to linear
Texture scaling off, but whatever "xBRZ" is is checked
Hardware transform on
Vertex cache on

Help is appreciated!