To build on Paul's reply, another solution (short of getting a new computer) is to buy an
EGPU, which currently will cost at least $200 - $300.
I used an eGPU for a while to boost the graphics performance of my Intel 13" MacBook Pro, and there are are a few things to know before going down this road.
The actual cost of an eGPU is considerably higher. Most eGPUs, including some of the ones linked, are empty enclosures with a card slot — at $200-300, the actual graphics card is not included. So you also have to figure out which Lightroom-compatible graphics card to put in the eGPU enclosure, and add its cost. The total cost can easily exceed $600 (even more if you need a card that can also accelerate video editing and 3D). That was (sort of) justifiable when Intel Macs were the only Macs, but now we have Apple Silicon Macs that come with good GPUs and more flexible graphics memory (thanks to Apple Silicon Unified Memory. When an eGPU today can cost $600+ just to accelerate a few features in Lightroom, you have to ask yourself if it might be better to sell the Intel Mac, combine the proceeds with what you would have spent on an eGPU and the graphics card to put in it, and apply that money to a new Apple Silicon Mac that would make everything faster.
Most eGPUs come with a half meter Thunderbolt cable, but that's so short you practically have to place the eGPU right next to the Mac, if your desk has that kind of room. If you need a longer Thunderbolt cable like a 2-meter one that lets you put the eGPU under the desk, you’ll have to buy it yourself…add at least $50 to your budget for one of those.
Of course an eGPU cannot help you use people masking on the go, because just about every eGPU out there is a bulky unit that requires AC power through a big power brick. Which is a problem if you might need to do people masking away from power outlets, and you won’t be able to use an eGPU on a train or airliner.
Also, there are technical complications. An eGPU works best when it drives an external display plugged into it; to have it accelerate the internal display of a laptop might need special configuration or might not be possible with certain models. And that reminds me that some hardware and applications are not compatible with eGPUs.
I got lucky, my eGPU was at the bottom end of the price scale, because I set it up before the severe graphics card shortage a couple of years ago that was brought on by cryptocurrency mining and pandemic supply chain bottlenecks. When that shortage came, assembling an eGPU could easily cost beyond $1000 because of the scarcity and high cost of graphics cards. Luckily things have improved, so prices are dropping.
If being able to use people masking is a serious need and Adobe does not find a way to lower the system requirements, given the cost, complexity, and inconvenience of an eGPU, now that we have Apple Silicon Macs picking up one of those is probably a better, overall cheaper, and more future-proof way for an Intel Mac user to get current graphics power. In terms of overall performance, an M1/M2 MacBook Air or Mac mini will blow away most Intel Macs ever made, with less heat/noise and better battery life, and 16GB unified memory or more should allow full GPU acceleration.
If you want a quick easy solution, you can try the Sonnet Breakaway Puck. It is a lot more compact that most eGPU enclosures, and the GPU is included (but permanently installed, so not upgradeable). For only 4GB VRAM (not very future proof) and all those limitations,
it starts at $500. A used Apple Silicon Mac is not much more.
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