LR Cat Size

But I have been told over the years that a very large catalog could slow things down.  I was wondering if things had changed. 

By @SRPcashie

Regardless of what the Adobe tech told you, what you were told was never true in the first place, even though it is widely repeated. If a catalog performs slowly in general, the cause is almost always something other than the file size of the catalog. For example, the catalog might need to be optimized (File > Optimize Catalog), or preview generation settings should be better matched to the hardware, or something else.

The link below is a great read about one catalog vs. many, from a very reputable Lightroom Classic authority. The article acknowledges that a large catalog can be slow, but only in certain specific ways, not in general; and it lists those specific limited ways (scroll down to “Why do some people recommend multiple catalogs?”).

https://www.lightroomqueen.com/one-or-multiple-catalogs/

That section ends by saying:

For most amateur photographers, the benefits of a single master catalog massively outweigh the disadvantages. Professional photographers may need to weigh the pros and cons a little more carefully and decide what’s right for their workflow.

But the bottom line is that, for most people, the default should not be multiple catalogs.

My own catalog, which I have been growing for 14 years since Lightroom version 1, is currently over 4.5GB cataloging over 150,000 photos and videos, and I think it performs quite well on my Apple M1 Pro processor that is 3 generations behind the latest models.

One of the biggest reasons I use one main catalog is that, for various purposes, I frequently need to gather photos across multiple years, for certain themes and projects. If I was to split my catalog into one for every year or two, it would become a massive headache to try and search for and collect photos across years because I would keep having to open different catalogs. (Much of this is because Lightroom Classic lets you open and search only one catalog at a time.) With one catalog, all the photos I have ever taken (including scans of old film) are always available all at once for searching, smart collections, slide shows, Print module projects, etc.

If you tend to do jobs that are never connected to each other and rarely referred to in the future, such as weddings or events for different clients, that is one reason to maybe use separate catalogs.

Something to keep in mind: Each major upgrade to Lightroom Classic typically requires a catalog format upgrade. If you maintain one catalog, every year you only have to perform one catalog format upgrade for your one catalog…easy, no problem, one and done.

But that leads to one of the biggest hassles with maintaining multiple catalogs: If you make a new catalog every 12 to 18 months, after a few years, each major upgrade will require you to upgrade more and more catalogs every time you open them. Someday you will want to upgrade to for example Lightroom Classic 25, and if after that upgrade you want to look for a photo and have to go through your now 20 catalogs, each catalog will ask you for a format upgrade when you open it, slowing you down, resulting in a new copy, multplying your catalogs (one for each version upgrade)… You’ll want to remember to archive or delete the old version catalogs, old version preview caches, etc. So over time, maintaning more catalogs can significantly complicate file management chores and take up storage.

Yes, Catalog etc on one drive and files on another ... I sometimes work with just the smart previews without the image file drive connected at all