Will an egpu help Lightroom render on my external display?

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I'm curious if investing in an eGPU through which to connect my external 27" 2560 x 1440 pixel display will help Lightroom Classic draw photos to the screen more quickly. I know it probably won't do anything for the actual editing work, but I was hoping it might speed up moving from one photo to another (even with use Smart Previews turned on, there is still a pause every several photos as it tries to transition to the next image).

I'm currently running on a 2018 MacBook Pro 13" with 2.7GHz Quad Core Processor, 16GB 2133MHz LPDDR3 RAM, 3.2 GB/s NVMe SSD, and integrated Intel Iris Plus Graphics 655 with 1536MB of VRAM (assuming that is shared RAM, but I'm actually not certain of that).

I've been slowly getting myself ready to switch back to Lightroom Classic from the CC Desktop app, and I'm remind of my effort to switch in the first place in order to get away from the slowness of Classic.
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Jon Anscher

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Posted 4 weeks ago

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dmeephd

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Everything I have read about using external GPUs with Macs is that it is only possible if your Mac has Thunderbolt 3, as Thunderbolt 2 was never designed to carry the bandwidth an eGPU requires.  (I have no  idea what your MacBook Pro has; mine is a 2013 with TB2.  So is my MacPro.)

I did a bit of research as I was interested in VR, and I hit that roadblock time and time again for my MacPro.  (A TB 2 to TB3 convertor buys us nothing to address the bandwidth; it's simply a connector interface adapter.)
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Jon Anscher

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Yeah all MacBook Pros produced since 2016 have Thunderbolt 3. I actually just recently replaced my 2013 15" MacBook Pro. It still is a solid machine, but with Quad Core in the 13" MacBooks now, I was ready to lightened up my load. Unfortunately, that also meant giving up my discrete graphics card. I really hope that wasn't a mistake. (That and not being able to get a hexacore and 32GB of RAM.)
(Edited)
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dmeephd

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Then you're good to go.  Just need to pick an eGPU which is compatible with the Mac OS.  They are few and far between.  Do your research carefully.  The VR sites seem to have this knowledge well documented and easy to find.
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Jon Anscher

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Yeah, the GPU selection is a whole other challenge. I really don't want to pay for the Blackmagic GPU, but I'm also not sure, we have two Thunderbolt 2 Displays, and as far as I can tell, the Blackmagic is the only one I can connect the video through the GPU to a Thunderbolt Display. I think all the others have Thunderbolt pass through, but then I wouldn't be taking advantage of running the display right off the video card. But I have to confirm that's really the case.

My bigger concern is whether it will actually do anything for increasing the speed. I'm not sure if the slowness is an issue of the graphics being drawn on the screen or of Lightroom doing the internal file work on the photo. I've read some reviews that say an eGPU may not do much for photo editing and can even make things worse.

Although I guess the advantage of the Blackmagic eGPU is that buying it from Apple offers a solid return policy. So if it doesn't work, I can bring it back. I'm still a little loathe to spend that much on a GPU box that can't be upgraded.