Sharpen AI GPU upgrade

Hi. I’m a new Sharpen AI user (less than two days) and I am very impressed; for ten years or more I have stuck with the sharpening tools in an old one-off-payment version of Lightroom, v4.4.1 but Sharpen AI beats my best efforts hands down, at least nine times from ten.

I am thinking of installing a new GPU, hoping to speed things up a bit. My budget probably limits me to 6Gb or 8Gb but first I’d be grateful if anyone could suggest what improvement I might expect, if any. I’m not very hardware savvy so please be gentle. I have searched this forum for previous threads on the topic but couldn’t find anything specific - if anything does exist, a link please?

Current system:
Windows 11, Intel i5 3.7GHz, 16Gb main memory, Radeon RX550 4Gb GPU.
Topaz Sharpen AI 4.1 Processing preferences set to Auto.

Some observations as it stands:
LR doesn’t appear to use GPU memory at all, which fits with my understanding of the version. I launch Sharpen AI from LR, passing a 16Mb RAW file as .tif; on return to LR, the .tif file is 115Mb.
Sharpen AI GPU usage peaks briefly at 60-70% while updating for tweaked blur/noise slider settings.
Sharpen AI GPU usage peaks briefly at 80-100% after zooming in or out and after switching from one view to another (single, split, comparison etc). Main memory usage usually sits at around 1.5Gb throughout while doing this but sometimes sits at 3Gb+.
While at rest, Sharpen AI uses 10% or less GPU and around 500Mb main memory - nothing else much was running while looking at these figures.
Switching between models takes 3-5 seconds - but that might have been measured after initial switches.
10-20 seconds for each of the four images when switching initially from single to comparison view - similar when switching from comparison to split; subsequently 5-10 seconds; this is one thing I would like to see faster.
Zooming in or out while in comparison view sometimes takes 30+ seconds per image, so two minutes overall; this is where I most want to see an improvement.
Applying the changes (return to Lightroom) takes about 30 seconds.

So, would the possible benefits from a new GPU be worth the outlay? 6 or 8 Gb? Thanks.