LrC on Apple Silicon — 48, 64, 96 or 128 GB: what does it actually use?

I’ve decided to move from Windows to a MacBook Pro. Apparently choosing the computer was the easy part — now I just have to decide how many kidneys the RAM upgrade is worth. :)

I'm trying to understand how Lightroom Classic (LrC) actually scales with unified memory on Apple Silicon. M1–M5 experiences are all useful, especially 48/64/96/128 GB+.

My current setup/workflow:

• i9-14900K → 64 GB DDR5 → RTX 4090 24 GB

• Canon R5 Mark II CR3s

• Heavy People masking → facial/body skin → hair → sclera → iris/pupil → clothes, etc.

• Transform Auto + local adjustments → Crop often late

My priority is Develop responsiveness — Crop, masks, Transform, zoom/pan and image switching — not export or Denoise.

I've seen the 4090's 24 GB VRAM fill while CPU/GPU usage remained surprisingly modest. Preliminary Apple Silicon testing also showed relatively modest CPU/GPU activity but much higher memory pressure than I expected.

For those monitoring with Activity Monitor, iStat or similar:

• How much memory does LrC actually use after a few hours?

• Memory pressure / swap?

• With 96/128 GB+, does LrC actually use the extra memory?

• Does it noticeably improve Develop responsiveness?

I'm interested in the general pattern across recent LrC and macOS versions, not isolated memory-leak bugs or one particularly bad release. Adobe has its moments; rolling back a troublesome version doesn't bother me.

Also: storage. For MacBook Pro users with 1–2 TB internally: catalog/previews internal + RAWs on fast Thunderbolt/USB4 SSD? Do you notice any Develop performance difference versus RAWs on the internal SSD?

If possible: Mac/SoC → RAM → memory pressure/swap → RAW location → monitoring tool.

Real-world numbers would be hugely appreciated.