Microstuttering + choppy, skipping frametimes

I've hardly seen anyone else mention this, but I'm having big, game-ruining microstuttering issues with the PC version of the game on Steam (haven't played the original). Regardless of the graphics settings, as I've tried everything from Ultra to Low presets in 1080p.

I have a 4-core i5 4590 CPU @ stock 3.3-3.7 GHz from 2014 and a Geforce 1660 Ti GPU, plus 16 GB of RAM. The rig seems more than enough (especially the GPU) to run this slightly updated 10-year old game maxed out, as it exceeds recommended specs, and most of the time it runs at a locked 60 fps. Also installed the latest 457.09 Nvidia drivers that specifically provide 'Day 1 support' for NFS HP Remastered.

However, quite regularly, especially in cases where there's multiple cars and large roadside objects on screen (e.g. night-time police event in the rain with loads of highway traffic), I get a regular microstuttering issue where the framerate only drops by about 5 fps or so, but the choppy, unsmooth feel of the stutters is really a joykiller and makes the game way less fun.

I've searched online and found threads about the original game from 2010 having identical problems on modern PCs with Windows 10, where it seems to put all the load on the first core (CPU 0) of a multicore CPU while ignoring the others. Apparently, in the original game, that could be solved by alt-tabbing out of the game and changing the CPU affinity in Task Manager - unchecking the CPU 0 core and only keeping cores 1-3 active, so the game would split the load between the other three cores.

I've tried that yesterday and while it initially seemed to work, I encountered a different, even worse issue twice after about 20 minutes of playing - the game would suddenly drop down to 3-4 fps, until I left the current race to the main menu and restarted the event.

I'll do some more testing, especially with MSI Afterburner to check whether the game's really only using one core of my CPU properly, but right now, it seems I'm stuck with either frequent microstuttering or the CPU affinity bypass, which works fine at first but seems to completely * the game after 15-20 minutes, prompting me to restart the event or the whole game.

What a mess, I sure hope they didn't actually carry over the same issue from the original game. What worries me most is that I don't see other users with the same problem in any threads online, and the Known issues from EA section doesn't even acknowledge the problem.

And please don't tell me my 4-core i5 4590 is the issue, it's above recommended specs and the problem is the same on both Low and Ultra settings, Fullscreen or Borderless, Vsync On or Off (I've tried all). I doubt it's a particular graphics setting that's causing it.