Sorry if I've gotten my technical terms mixed here. I'm meaning once you've finished a project in PP and then hit Export which then queues it into Media Encoder for rendering. Its the last stage here thats slow.
Versions are both 2015.3
Well, you may have a GT 630 that's really a rebadged GT 440. In addition, the GT 630 may have firmware that is either incompatible with UEFI or requires CSM (Compatibility Support Module) to be enabled in order to work properly on a UEFI system. And then, your Dell PC may have a legacy BIOS or a hybrid EFI BIOS instead of a true UEFI implementation. In such a case, then, Premiere's MPE (Mercury Playback Engine) renderer will be "permanently" locked to the software-only mode, which will result in extremely long render times. So will having only 4GB of RAM, which will also "permanently" lock Premiere's renderer to the MPE software-only mode.
Thus, you will need to not only add more RAM to your system, but also upgrade your system's GPU to a newer one.
In addition, I noticed that the CPU utilization is very low, which means that your system's bottleneck is likely not in the hardware per se, but somewhere else in your system, such as improper or poor tuning that allows an excessive number of processes which often prevent an otherwise CPU-intensive process from accessing its full resources.