Jumping Framerates?

[Turninwheels4x4]

I've noticed, that when playing games (Midnight Club 3 and L.A. Remix mostly) that, depending on my luck, the game will either run normally (a few FPS dips here and there, compensated by frameskip) or it'll run in a way that If it doesn't get 60fps, it'll immediately jump down to 30. This sounds like a vsync problem, or maybe some external software is doing it, but no. Vsync is off (turning it on doesn't actually enable vsync; bug?) and the only other software that could possibly affect framerate is msi afterburner, and i've tried playing with it running in the background, and without it. I've also noticed that changing the emulated clock speed sometimes fixes this (but only at 666mhz?). Normally I wouldn't complain about stuff like this, but due to my PC being at the performance level of barely 60fps, as soon as I dip to, say, 59, it'll immediately jump to 30, causing a wierd form of stuttering.
Settings:

Code:

Backend: Vulcan
Mode: Buffered Rendering
Simulate block transfer effects: True
Software rendering (slow): Greyed out and  False
Frameskipping: 4
Auto Frameskip: True
Prevent FPS from exceeding 60 (speeds up GoW): False
Alternative speed: 50%
Postprocessing shader: Off
Fullscreen: True
Rendering resolution: 1:1 (1920x1080@60hz)
Vsync: False
Hardware Transform: True
Software skinning: True
Vertex Cache: True
Lazy texture caching (speedup): False
Retain cheanged textures (sometimes slower): False
Disable slower effects: False
Spline/Bezier curves quality: Greyed out; High
Hardware tessellation (expirimental): True
Upscale level: off
Upscale type: xBRZ
Deposterize: False
Antisotropic filtering: off
Texture filtering: Auto
Screen scaling filter: Nearest
Timer Hack: False
Disable Stencil test: False
Lower resolution for effects(reduces artifacts): off
Fps counter: FPS
Show debug statistics: False
Audio is enabled with low latency
All settings in System are defaults, except for the emulated clock speed (666mhz), the nickname of the psp (Turner), cheats are enabled (draw distance fix), and it caches the ISO in ram.

PC Specs:

Code:

CPU: i5-2400 @ 3.1ghz 4 cores, 4 threads
GPU: Nvidia Geforce GT740, 2gb Vram, 1000mhz clock
10Gb of generic DDR3 RAM
120gb ssd, 1tb hdd
running windows 10 Pro x64