2x GTX980 slow down in 10.13.4

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Hi all,

A few weeks ago I've finally got the courage and time to upgrade my Sierra to High Sierra. My 2 x GTX 980 worked perfectly in Sierra with no slowdowns whatsoever, but they appear to be problematic in the new OS version.
In Chrome, it is very often (for example, when viewing macrumors, or facebook videos), the window would almost freeze and become insanely slow. And since FCPX's UI doesn't render properly, I am suspecting that it's the GPU's problem rather than Chrome.
Can anyone point me to anything that would help with the situation? It is actually becoming really annoying and I had to use my MacBook Pro for a lot of the tasks because of this.
Currently set up as Mac6,1 with SSDT injection for both GPUs as GFX1. Running the Nvidia web driver 387.10.10.10.30.107

Stevens-Mac-Pro:~ steven$ kextstat | grep Lilu
   29    1 0xffffff7f8326e000 0x1f000    0x1f000    as.vit9696.Lilu (1.2.3) 9C714621-4E3B-37F7-9439-49FB5355317B <7 5 4 3 2 1>
Stevens-Mac-Pro:~ steven$ kextstat | grep Nvidia
   30    0 0xffffff7f8328d000 0xb000     0xb000     as.lvs1974.NvidiaGraphicsFixup (1.2.5) E82C5AC8-98E2-37EC-A62B-E79037A10D32 <29 7 5 4 3 2 1>
Stevens-Mac-Pro:~ steven$ kextstat | grep Web
  127    2 0xffffff7f80b90000 0x679000   0x679000   com.nvidia.web.NVDAResmanWeb (10.3.1) AFE86340-E203-383D-96E6-22C063DC6556 <111 100 99 12 7 5 4 3 1>
  128    0 0xffffff7f81ca3000 0xa8000    0xa8000    com.nvidia.web.GeForceWeb (10.3.1) A4EAB8FE-69E5-34E3-A95F-FB2B21101604 <127 113 100 99 12 7 5 4 3 1>
  129    0 0xffffff7f81407000 0x1a4000   0x1a4000   com.nvidia.web.NVDAGM100HalWeb (10.3.1) 16BD04F0-8B47-3565-B416-680CAD199D22 <127 12 4 3>

If this doesn't get resolved soon I am honestly just going to downgrade to Sierra. APFS isn't worth this.

Thanks in advance!

 

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For reference, I'm running 3x 4K LG displays via DisplayPort, and a 1200p display via HDMI. They are all attached to the same GPU (the other one has nothing attached to it).