Adobe Premiere Pro LONG exporting time and 100% GPU.

The problem is the Quadro P620 itself. It is much too weak by current standards. In fact, it is just a lower-clocked and cut-down GeForce GTX 1050 with only 512 CUDA cores (versus 640 CUDA cores in the GTX 1050) and slower VRAM - and that even the GTX 1050 itself is barely well-matched to even the slowest, weakest CPU of its era that's not a Pentium or a Celeron in terms of performance. And if the GPU usage is pinned to 100% while the CPU usage is much less than full, this means that you have a serious GPU-to-CPU performance mismatch in your PC (that is, your system is wholly bottlenecked by the GPU).

That P62O GPU is a six year old one ... I don't think Nvidia supports them anymore. And even if it is, only 4GB of vRAM is simply not enough for the current versions of any pro video post app.

And 16GB of RAM total ... well, don't expect to work above 1280x720 really.

That system is sadly out of date.

What are the hard drives (how many, what kind, what is on each, what capacity, and how full)?

Please post , Premiere version and build, MediaInfo info in Treeview on footage used, sequence settings and export settings.

https://mediaarea.net/en/MediaInfo