VLC suddenly lags when playing HEVC

[JeffJ]

I'm having a very weird issue; out of no where, my computer is suddenly having major issues playing a 1080p x265 HEVC movie in VLC. It worked fine a couple of days ago, but now, all of a sudden, playing the exact same file(s) in VLC will make the video lag and stutter like crazy, and it's filled with artefacts. The audio is fine.

 

The weird thing is, if I play it in Windows Media Player, it runs almost perfectly (HBO logo in the beginning of the video lags a little, but that's about it). But, once again, just a few days ago, it was perfect in VLC. I haven't installed anything new since then.

Things I have tried:

  1: Running scans with Windows Defender (came up clean)

  2: Running a few swipes on the disks and the registry with CCleaner
  3: Enabling/disabling hardware encoding in VLC (doesn't seem to make the slightest difference either way)
  4: Monitored my performance closely - as of this writing it's sitting at 3-6% CPU usage and 9% memory usage. Disks are all operating normally.
  5: Disabling all but the most necessary startup tasks so no weird things are booting up with Windows

  6: Playing the file(s) from a different disk just to rule out if the disk was too slow or something like that
  7: Uninstalling and reinstalling VLC (I am running version 2.2.4)

  8: Updating nVidia graphics cards drivers (currently on version 368.39)

All other files are playing just fine, it's just these highly CPU intense HEVC files, so I can't help but wonder if somehow my CPU is being crippled somewhere, but I just can't put my finger on it. Playing things like GTA V on maximum settings with lots of explosions etc. runs just fine, and like I said, playing the same things in Windows Media Player is almost flawless, so this is a really weird issue.

I'm not 100% sure if the rest of my computing operations (browsing, gaming etc.) seems to be a little slower too or if I'm just imagining things now. Although, not sure if related, but I do seem to have gotten some screen tearing when scrolling in Chrome too, right around the same time. Things do seem a little bit slower all around, so once again, I can't help but suspect some type of really weird malware/virus.

And before you ask, I know it seems obvious to say "why don't you just watch it in Windows Media Player then", but this is clearly a problem that needs to be fixed since it worked just fine a couple of days ago (also, the non-external subtitles won't work in WMP)

This is my setup:

ASUS Z170 Deluxe

Intel i7-6700K 4.0 Ghz Skylake

64GB DDR4 RAM

2 x GeForce 980Ti (ASUS Strix OC edition)

2 x Samsung 850 SSD

2 x WD Black HDD

SeaSonic 1200W 80+ Platinum
OS: Windows 10 64 bit