Lightroom Classic, Macbook Air & High Memory Usage

Hi, sorry I haven’t followed up with your earlier replies, been very busy.

I do not think the size of the catalog should be the reason. How many photos are in it? Mine has over 150,000 photos and videos at this point, and it isn’t causing unexpected memory problems.

This is exact pop up I get. Activity monitor seems to run at yellow all the time, it does drop briefly to green after CleanMyMac does it's thing, then soon returns to yellow. 

By @lyndseya54518626

OK. The CleanMyMac message is expressing concern about “RAM + swap.” I actually question that, because if they are only measuring those two things, that’s an outdated way to evaluate Mac memory usage.

Activity Monitor is more informative. Memory Pressure is a holistic look at the three ways that macOS handles memory demands: Physical (installed) memory, compressed memory, and swap memory. I may be wrong but it looks like CleanMyMac is both not accounting for compressed memory (because it doesn’t mention it), and over-weighting free physical memory.

Looking at the graph at the bottom of the Memory tab in Activity Monitor:

Physical Memory is what’s actually installed. If your Mac has 16GB, that’s the Physical Memory. Now, years ago, if you had 16GB and 15GB was used, utilities like CleanMyMac would warn of “low free RAM.” That was true back then, but today that’s less of a concern because of the ways macOS manages memory. If there is high demand for memory, macOS will next compress the contents of memory, so that for example, 1GB of physical memory is now handling 8GB of compressed memory. This is fine, and works quickly because of how powerful the processors are now. If that starts to get strained, then macOS starts to swap memory to storage, which is where swap comes from. As long as this system can handle the load, Memory Pressure is green.

In the Activity Monitor processes list, the Memory column is a total amount an app uses across the three resources, not just physical memory. That’s why it’s possible to see an application to report using more memory than is physically installed in the Mac. It’s possible because some of the memory it’s using is compressed or swapped.

If memory demands are very high, that act of juggling data between Physical, Compressed, and Swap can get too complicated. That is when Memory Pressure turns yellow, or even red if it’s really bad.

I think a constructive way to think about it is this:

• If Memory Pressure is yellow, but you don’t see any problems, and if it is green most of the time, things are OK. 
• If Memory Pressure is yellow fairly often, and you notice slowdowns and crashing, things are not OK and something needs to be addressed. 
• If Memory Pressure is red, there are likely to be problems even if you don’t notice them yet. 

Regarding CleanMyMac:

• If CleanMyMac’s warnings track pretty consistently with Memory Pressure going high yellow or red, then I suppose the CleanMyMac alert means something. But I wouldn’t assume the worst without also checking the situation in Activity Monitor.  
• If CleanMyMac’s warnings appear even if Memory Pressure is green, I would conclude CleanMyMac is not using an up-to-date method to monitor Mac memory, which would mean their alerts are not useful. One thing that makes me question CleanMyMac is that low free physical memory and high swap usage do not, by themselves, necessarily indicate an immediate problem. That is why I’m interested in whether CleanMyMac is alerting too soon compared to Activity Monitor. 

If there are serious problems directly related to memory, memory can’t be upgraded in a Mac laptop after purchase, so the only route is to get a new one with more memory (and maybe sell the current one to help pay for the replacement, unless the current one is still within the return period). But 16GB in an M2 should be quite usable for Lightroom Classic unless your individual images are very large (like well above 40 megapixels), or if you keep many applications open.

The other thing is that there are posts here about people seeing unusual, alarmingly high spikes in Lightroom Classic memory usage that are not expected. If this turns out to be a bug and you’re seeing a form of it, it is possible that’s going to get fixed anyway, in which case you wouldn’t have to do anything. But we’ll have to wait and see on that one.