My 16GB M1 Mini, as I said, with hours of use (because it is sometimes my workflow for the day), would leave me just waiting for previews to load due to RAM issues. I believe you and the previous person that Lightroom is working just fine for you and the other person who is using it with 8GB, but my workflow is a testament that it totally depends on how you use it.
Hrm.
From where I sit, "how you use it" = "doing what Adobe tells you to do." More specifically: it means respecting both the nuance and the broader picture of what they're telling you.
So: Adobe says you should speed your overall Lightroom Library module workflow by generating previews on import (I prefer 1:1), by
retaining those previews as long as you're working with the relevant photos (note that default catalog preference settings automatically discard your previews after a short time), by storing your previews on a fast, preferably local / internal SSD, and by giving Lightroom a generous maximum disk cache.
Step back and see the broader picture: if you want the best possible performance from Lightroom Classic, on any hardware,
your workflow has to be mindful of previews. You have to know what they are. You have to know which ones Lightroom uses, where, when, why. Your workflow has to guarantee they're available when you--and Lightroom--need them.
If you discard previews before you're done working with a photo collection, or if you allow default catalog preference settings to discard them on your behalf, or if you didn't generate them to begin with, or if you generated larger or smaller previews than your workflow actually needs, or if you've stored previews on a slow disk, or if you're running a small Camera Raw max cache size, then your experience will suffer--regardless of your hardware specs.
Why does an M1 Pro with 16GB of RAM lag in the Library module, while an ancient intel i5 Macbook from 2015 with 8GB of ram flies through it? This is why--this is the grist of "how you use it."
Adobe also reminds you to speed your develop module performance by generating Smart Previews on import and by editing with them whenever you can. You can do this either by checking the "Use Smart Previews" option in preferences or by simply storing your catalog's RAW file library on an external volume you can eject; when you unmount the volume, Lightroom will simply default to working with Smart Previews.
If we step back and realize what Adobe's Smart Previews are--tiny 4-ish megapixel proxy files--it's obvious that almost any decent computer made in the last dozen-or-so years will have no problem whatsoever slicing-and-dicing them. Doesn't matter how big the original RAW files are. If any computer is laggy from the get-go with Lightroom's develop module, it's clearly because Smart Previews aren't being leveraged as Adobe intended.
So far as I can tell, the only real usage note with Smart Previews involves 1:1 pixel edit adjustments like sharpening, grain effects, or high-precision mask fringes. If you're working with Smart Previews only and your original RAW files are on an unmounted volume, the develop module's 1:1 zoom will show you the smaller four-megapixel Smart Preview; so you may need to mount your library volume and zoom to the original file's full resolution to adjust your few high-precision edits to taste. Even so, that means finishing only one or two adjustments with a full-resolution file. (And for what it's worth, I would also note that many of the editors with whom I work ultimately prefer the look of sharpening and grain adjustments made at Smart Preview resolution, even if they're ultimately delivering a 50+ megapixel finished result. Adobe picked the Smart Preview proxy size strategically, for this reason--small enough to dramatically improve performance and consume negligible storage space, big enough to offer sound perspective on every slider in the develop module.)
Adobe also points out that the
order in which you make RAW image adjustments can have significant implications for the overall performance of the Lightroom develop module. Over the years I have found that, beyond defaulting to work with Smart Previews, this is probably
the single most impactful performance tip they offer, in terms of maintaining a snappy overall feel in daily editing work. I found the order they recommend to be a little counter-intuitive at first; I wouldn't necessarily have stumbled upon it myself through trial-and-error. Basically: spot / clone / heal
first, then profile, then global adjustments, then masks, then sharpen. Within the "basic" panel itself, it's particularly important to apply sliders that combine tone and small-radius unsharp calculations (shadows, highlights, blacks, whites, clarity, texture, dehaze)
after spot / clone / heal adjustments rather than before, and
before sharpening rather than after. Through a decade of exploring these order recommendations (Adobe first posted them in 2012!) what I've mostly noticed is that the largest impact often boils down to "Sharpen Last," or, conversely, "every slider, brush, and mask is gonna be laggy if you sharpen first."
Next: yes all the web's talking-photographer-heads hate DNGs, but I've found that converting RAW files to DNG on import lubricates every aspect of Lightroom performance thereafter. (Again, predictably.) It speeds the library module, speeds the develop module, speeds batch export
enormously--on my Macbook by a factor of at least 2x. (And if you insist on retaining unmolested OEM-format RAW files, it's obviously no big deal to back up your originals--we all probably do this, already.)
Finally, Adobe suggests a number of little Lightroom workflow habits that can add up to a significantly improved performance experience over time. Two of these that I've found to be particularly impactful over the years: (1) periodically clearing long photo edit history lists and using snapshots, instead, to index a frame's important edit or comparison steps. Short edit history lists per frame = dramatically smaller catalog files = quicker develop
and library modules.
And, (2) in the develop module, Adobe suggests using the process version that offers only the features your edit actually needs, or using different process versions strategically at different points during an edit. Adobe's first process version, introduced all the way back in 2003 (!!!) was designed to run on the hardware of the time--so any develop module work you do with it will be
lightning-instant quick on a modern computer. Same goes for version 2 (PV2010) and version 3 (PV2012). If your edit won't use custom color profiles or require AI mask setups, for example, then you can deploy the whole of the contemporary Lightroom Develop feature set at dramatically improved speed by flipping into process version 3 (PV2012). Or, you can use multiple process versions over the course of an edit, strategically: you might, for example, flip a photo into version 1 (PV2003) to guarantee that a run of 100 spot-clone-heal adjustments will proceed fast-and-fluidly (e.g. when you're retouching a portrait), and with that finished you'd then flip the process switch back to version 6 to choose a modern custom color profile and set up your AI masks. Of course, when you then export your finished result, every edit step you made--including the spot-clone-heal adjustments--will be rendered using version 6.
If you use Lightroom for all-day edit sessions--as you say you do--then these are the "how you use it" considerations that really matter; they're also the behaviors that the hardware-performance-police never seem to incorporate in their measurements and arguments, never seem to understand or know especially well, themselves.
Truth is, "how you use it" is gritty stuff. It's all detail and nuance. It takes a wall of text to circle back toward the bigger picture. (I mean, the
order in which you make your Lightroom develop module edits! Crazy, right? Who ever talks about that on youtube when they're doing a performance demo? NOBODY) Who'll even read this tedious post? It's decidedly
unglamorous.
But it's how the job actually gets done, how you actually figure out what hardware you need.
¯\_(ツ)_/¯
