Same old Dropped Frames / Slow Performance question on a high spec machine.

Don't throw away anything just yet. I would definitely be inclined that your GPU is largely to blame. You see, that GeForce GTX 1050 Ti itself is severely mismatched to any modern 8-core/16-thread CPU to begin with. In fact, it is so mismatched to the CPU that it actually chokes the life out of everything else that runs on that system. This condition is called a bottleneck, where one underperformance component drags down the performance of everything else in that PC. Simply put, that CPU/GPU combo is like driving a European sports sedan with all four of its tyres half-deflated. That 1050 Ti would have been a good match to only a 4-core/4-thread CPU.

As a matter of fact, moving up to a higher-end GPU of the exact same generation will not improve matters sufficiently to justify the price that you would be paying for such a same-generation GPU upgrade because all of Nvidia's GPUs up to and including Pascal (the GeForce 10 series) are weaklings by current standards. You will actually need a newer-generation GeForce GPU than that 1050 Ti in order to bring your system's overall performance up to par.

Unfortunately, you are stuck between a rock and a hard place if your total upgrade budget is limited: The properly matched (performance-wise) GPU for a 3rd-Generation 8-core/16-thread Ryzen would have cost you more than $500 by itself. (I am talking about the GeForce RTX 2070 SUPER, in this case.) However, for 2020 and later versions of Premiere Pro, even a $150-ish GTX 1650 SUPER would outperform even a GeForce GTX 1080 Ti (if the scores from the PugetBench for Premiere Pro 0.9 are to be believed).

All in all, this is a perfect example of poor component budgeting, especially by someone who believes that video editing programs even today make little if any use whatsoever of the GPU. For the budget whomever configured it spent so much money on a powerful CPU that it left little if any budget remaining for the rest of the core components of that system. In fact, for that total budget that you had spent on this imbalanced build I would have instead picked a 6-core CPU instead of an 8-core CPU but chosen a non-SUPER RTX 2060 instead of that now-outdated GTX 1050 Ti.

And I had known the posts by the late Harm Millaard (who had passed away four years ago) about component balance. Especially in a video editing system, all of the major core components should closely match one another in terms of relative performance. This build, however, is a very classic example of how not to configure a video editing build.

What kind of media are you working with? What are the specs of it? (resolution, framerate, codec, where is it from?)

What kind of proxies did you create? In most situations that should help your playback a lot assuming it's an intermediate codec at low bitrate.