P: High CPU usage makes it unusable during export

"My CPU usage on Activity monitor registers anywhere from 750% to +1400% - I don't even know how that's possible"

In % CPU column of Activity Monitor, 100% = one virtual (logical) core / thread / processor (industry terminology is not consistent).  So on an Intel computer with 16 virtual (logical) cores / threads / processors, the % CPU column could show a maximum of 1600% for Lightroom.

But in the system totals shown at the bottom, System + User + Idle total to 100%.  How's that for confusing?

I moved from a 2009 Mac Pro to a brand new iMac i9 with 40GB of RAM working off a 1TB SSD.  My 2009 was almost as fast and never had issues like this using the newer LR Classic.  I can't even write a text message and have trouble mousing while trying to export just 800 images.  Same concerns here - I can settle for a slower export. But I can't stop working for hours at a time throughout the day.  My CPU usage on Activity monitor registers anywhere from 750% to +1400% - I don't even know how that's possible

I have to export 1500 images  - it doesn't matter whether they are exported a bit later. I could start that in the morning and meanwhile work on other jobs inside and outside of LR. BUT I can't do anything useful for a few hours, because LR is even slowing down my browser and email-client. So I have to postpone the export for during the night.

After all I have the final images later (next morning), than I would have had them if the export ran in the background during the day (afternoon). So anyone who came up with that CPU-Usage Idea obviously didn't give much thought to real live. Does Adobe ever test anything in real life environments? Seems to me, they just rely on users wasting their time in forums instead of being productive.

I'd say make Export a lower CPU-priority by default with an option to switch up and block the rest of your machine, if the user so chooses.

Rober Frost,
In terms of computing, the export thread should not use that much CPU. LR will use all of your CPU either.
On the other hand, there are countless LR users who simply want to start working on the next set of photos (so they can enjoy their book and coffee sooner).

I want to keep working on other images or in other programs during export. Please give me the choice.

And CPU usage seems to change over time somehow. Its always over 90% but after a while the other programs run smoother again??? on PC.

You may find you're running into bottlenecks elsewhere of course. For example, storage and available memory. Holding 12 consecutive images in memory and applying all the changes soon adds up. Thus, your CPUs aren't being fed as they should.

If you want to set low priority for the export process, make your own shortcut to turn LR on with export at low priority as in the following 

https://www.eightforums.com/threads/cpu-priority-shortcut-for-a-program-create-in-windows.40287/

Bob Frost

Surprisingly it doesn't cut performance in half! Exporting 65 nefs using 12 threads took 4 min 20 secs, while using 6 threads it took 3 mins 45 secs. Intel is now selling cpus with hyperthreading permanently disabled. It can cause more problems than it solves. And Intel has recently been advocating turning hyperthreading off to reduce vulnerability to security problems, and is moving away from hyperthreading in some of its latest processors.

But I love having all my 12 threads at 100% while exporting or rendering previews. No doubt adobe could have a checkbox for exports as they do for previews.That would make both of us happy.

Bob Frost

Turning off half the threads is kinda ridiculous - if you're on a 16-thread machine, you're cutting all that fantastic performance in half. Setting Low priority for the process is less negative impact.

If you go to Puget Systems website (pugetsystems.com) you will find that they have an article about turning off half the cpu threads for LR, and have produced a utility that launches LR with half the threads. It is not permanent; you just launch LR from this utility (put it on your desktop) when you want to do exports, and in most cases it slows down exports and leaves half your threads free for other purposes. Its not what they designed the utility for (as you will see when you read the article), but I realised it might just be what you posters want. I've tried it and it only allows LR to use half the threads, slowing down export a little, but the other threads are free for other programs.

Bob Frost