Unstable FPS Problem

[Komus]

Hello,

I have a problem that is affecting every game I play with Dolphin (Wind Waker, Monkey Ball Adventure, Kirby Returns to Dreamland). During gameplay, FPS (not VPS) will go down randomly every 5-10 seconds or so from 60 to 30-40, but if I don't do anything it goes back to 60.
I tried to mess with graphics and audio settings (OpenGL/Direct3D/1x IR/4x IR/VSync/no hacks/with hacks/HLE/LLE etc.) but the problem still persists regardless of any combination used. I also tried disabling Hyperthreading but I don't find any option in the BIOS to disable it, setting affinity to only two processors is also not affecting anything. Choosing the maximum performance setting in Power Management and in my NVIDIA Control Panel doesn't affect anything too.

Is there anything I missed that could somehow mess with this?
Despite searching through the forums, I can't find anyone having the same problem I have. I'm sorry if it has been already asked and solved.

Config:
ASUS G750JX
Windows 8.1 x64
Intel Core i7 4700HQ 2.4 GHz (@3.4 GHz with Turbo Boost)
NVIDIA Geforce GTX 770M
16GB RAM
Builds used : Dolphin 4.0-773, 4.0.2, 4.0.1

Thanks!

[Anti-Ultimate]

overheating notebook

[mbc07]

Check your temperatures, your CPU may be throttling back due overheat...

EDIT: Ninja'd. Again

[Komus]

Temperature stays around 70-76°C during gameplay, is this enough for overheating?

[DJBarry004]

No, but it could be near to that...

[Komus]

It's not a slowdown problem like the emulator makes the game slower and the sound is crackling, it's a slowdown like on normal games where it skips frames, nothing to do with VPS. I also tested Wind Waker and Kirby without the framelimiter and there's no sign of the CPU "slowing down itself" where there's a big slowdown in the middle of the game.

[Anti-Ultimate]

So the sound isn't crackling and it looks more like it's just skipping frames?

[Komus]

Yes, like this. The sound is not crackling at all. I don't know if "suttering" is the right word.
Also, when VSync is disabled, the emulator shows 60 FPS sometimes going down to 53 even though it's way worse, and when VSync is enabled it shows the FPS varying between 40-60 sometimes going down to 30, which I feel is more accurate. Again VPS stays at 60. It's like it stays at 60 FPS for 10 secs, and then 5 seconds at 40, 10 at 60 etc.
This is not something that happen after like 30 minutes of gameplay. It's right after 5-10 seconds.

[DJBarry004]

Do you have Virtual XFB enabled?

[Komus]

No, it's disabled.