Sudden (and permanent) Framerate Drop (from 42+ down to 11-16) After BF4 Crashed

[Z0MGbies]

My laptop has 8GB RAM, 2GB Nvidia 840M GPU, i7-5500U CPU - Running 64 Bit Windows 10.

Here is a link to the laptop model I am using.

YouTube video of the same system (with an i5 CPU) getting 20% higher FPS than I ever got.

All week I've been playing BF4 without an issue.  My framerate has been 40 or higher at all times (with the odd exception).  Today I played 1 or 2 games, and as it transitioned to the next game the whole thing froze.  I had the black screen between games with the flashing "_" but the whole system was unresponsive, incl CTRL+ALT+DEL.  After a 2 mins I had to just hold the power button to reboot the computer.

After it rebooted, I logged back into a server and all of a sudden I was getting 14fps, with the odd spike to 16 if I was lucky (30Hz server with 1 player, on Operation Locker, and others).  It will often stutter like when you knock a stylus on a vinyl record while loading now, too (the music will pl-pl-play the sa-sa-same note over an-an-and over).

I've tried the following (mixing and matching where relevant):

1. Changing the graphics settings to Low from Medium
2. Reinstalled DirectX from the BF4 files
3. Reinstalled Visual Basic from the BF4 files (64 and 32 bit)
4. Reinstalled the same video card driver I had when I was getting 40-52 FPS (which is also the latest one).
5. Uninstalled the last Windows update
6. REinstalled the last windows update
7. Reinstalled punkbuster
8. Ended all non-essential processes
9. Ensured Nvidia was selected for use in the Nvidia control panel
10. Ensured the video card was still on Performance>Quality
11. Turned off HP Smart Sense (bloatware to keep your legs from getting too warm if its on your lap by reducing performance)
12. Double checked power/performance plan settings in windows, to ensure it prioritised performance
13. Run "sfc /scannow" with no errors
14. Installed a user.cfg file
15. Used a PROFSAVE_profile file
16. Tested on multiple 30Hz servers, including both empty and full ones on a variety of maps
17. Set CPU priority to HIGH using Task Manager
18. Checked battery is securely in and the laptop is plugged in
19. Several reboots and clean boots

NOTHING has improved the FPS at all.

I am currently in the middle of re-downloading the game to reinstall it, but I'm very doubtful it will change anything.

What's gone wrong? How can I fix it?

[WootCandy]

It sounds like it's using the HD5500 IGP on the i7 despite the settings to force the 840m.

Try to confirm it's using the 840m with monitoring software like Open Hardware Monitor, GPU-Z, or Afterburner (without RiviaTuner because it causes issues with Origin in Game if not set to None-Detection).