Having no clue to the material you're rendering, there's no way I can guess if or whether you have a problem there or not.

The GPU only does certain things ... and the vast majority of rendering work does not involve the GPU. So ... again ... GPU's are used for scaling frame-sizes, Lumetri & some other color effects, and a few other things. There's a list of GPU-accelerated effects, and if your sequence doesn't use those items continuously, you'll not see a big difference in render times.

Second ... even if you are using GPU accelerated effects, if the rest or your computer's hardware isn't up to passing data forth & back rapidly on a sustained basis, you'll still have those bottlenecks.

The typical plan for working with PrPro up until recent months has been built on using either 4-6 separate drives with high-speed connections to the motherboard or a 4-8 drive RAID 0 stripped array for data in/out sustained speeds, along with a ton of RAM, and at least four physical cores to the CPU. One dispersed major sections of the PrPro data-chain around those drives, each to a separate drive to avoid read/write issues, such as OS/programs; media cache & media cache database; previews; project files; media; and exports, on up to that many different drives.

New tech is coming into the drives, so there are some situations where the right make/model of say an NVMe or m.2 drive can sustain such a high read/write number that it can replace several to all of the old-style layout of project parts.

So ... what kind of media and effects are you using, and what is the total hardware of that computer? And how are you laying out the parts of the PrPro workflow?

Neil