Zotero 7 beta | High memory/CPU usage when reading PDF with external display

edited January 26, 2024
Platform: Macbook Air M1 8G 2020

*edit* System: macOS Sonoma 14.1

*edit* Z7 versions that have this glitch: from beta.somewhere to beta.55

Issue: I usually connect a 4K external display (3840 * 2610) to my Mac. When I read PDFs (just typical academic papers, especially review articles with >20 pages) with odd spreads and scroll down for several pages, the PDF reviewer would become extremely laggy and my laptop burns like hell. I checked the activity monitor, and it tells that Zotero is taking >70% CPU and >5G memory usage. This is abnormal.

Then I disconnected the external display and try to read them on my Mac's screen. This time everything goes well and no issues at all. I noticed an obvious change: when I read PDFs with external display, the PDF reviewer tends to save those pages I have scrolled over, so when I scroll back, the pages are still there, and no loading was needed. However, when I use my Mac's own display, the PDF reviewer seems to delete those pages that are not currently on screen, and when I scroll back, they would be reloaded. I assume there's some bugs that let Zotero keep saving the unnecessary pages when it's connected to external display, which causes this issue?

I have been using Z7 beta from beta 1. From my experience, this issue has been there for like few months, but it did not happen from the first few beta releases.

*edit* I turned off all the plugins, and I still have the same issue.

*edit* After test, I think the laggy issue comes when I set the PDF reader to full screen (3840 * 2610). If the PDF reader only occupies half of the screen of my external display, it is very smooth. But I still don't know if it's the performance issue of Z7 or my Mac.
  • I have this problem too, very laggy and over 2Gb of RAM usage. This problem occurred after the interface was updated.
  • *Cannot* confirm.
    Apple MacBook Air M1 2020 16 GB, Mac OS 13.6.4:

    * No difference with or without external monitor (2560x1440 27 inch 75 Hz)
    * Yes, when scrolling fast through a PDF (or ePub), I can "scare up" Zotero CPU usage to high levels, even 134 %, but then goes back to 4 % or so.
    * I get equal readings when opening same PDF in Apples Preview and scroll fast in the same way, CPU temporarily shoots high up, but goes back.
    * No lags noticed, I haven't inspected CPU for Zotero until this thread since I have not experienced any problems, but maybe my 16 GB RAM helps. RAM usage for Zotero 1,84 GB (with a few PDFs open), going up to 2,11 GB when scrolling fast through a book.
  • Which version of Zotero is this exactly? I've noticed that on my computers (Linux), the PDF viewer feels massively faster on beta 55 compared to previous versions.
  • edited January 26, 2024
    I w/o problems, the brand new beta release:
  • Maybe look at this thread? Mac user w high CPU usage w PDFs. Turned out to be a plug-in.
  • @otexplorer Hi, thanks for the valuable comments. I turned off all the plugins and restarted zotero7 beta.55. Then I opened a review article of 55 pages and fast scroll it. I can still encounter the same issue with 144.7% CPU and 4.22 GB memory usage. My laptop still burns ang lags.

    I also tested the same doc on apple's preview, PSDF's PDF viewer, and readdle's PDF expert. Very smooth and no issue at all.
  • Hi, new user here. I love Zotero 6 (especially compared to what I was using before), and I really like Z7 too. But I agree with the others here that the PDF viewing experience on Z7 is slightly laggy compared to the current stable version of Z6. Brand new installation, no plugins, just a PDF with annotations.

    I can't stress enough how awesome Zotero is as a reference manager, I have been raving to my colleagues about it. I just wanted to chime in with this tiny issue so hopefully developers can zero in on what's going on.
  • @n9631411: Can you send the PDF in question to support@zotero.org with a link to this thread? Also, what OS? Does it happen with a new copy without annotations?

    Zotero 7 should generally be much faster than Zotero 6, including in the reader.
  • Hi dstillman,

    Sure I can send the PDF through, though it's not really isolated to any particular one. I'm running Zotero on M1 Pro and M2 Pro macs running macOS 14.3.

    I just feel that there's a very small amount of stutter when scrolling quickly through a PDF, annotations or not. Visually, it looks like "dropped frames" if that would be the correct way to describe it. When directly compared to the built in macOS Preview app it is more noticeable, though I understand this might not be a fair comparison as the programs do different amounts of work. I did notice something similar in Z6 when I double checked, but I have to stress, for me it's a very minor thing.
  • Yes, the only relevant comparison would be to Zotero 6 — it’s not going to be as fast as Preview. But it should be faster than Zotero 6 in all respects, and if not we’d want to know.
  • Hi, macOS Sonoma MBP M1 2020 here, testing Zotero 7 with auto-sync disabled, an empty library with just one small pdf attached and open, I keep Activity Monitor in a separate desktop so that Zotero is not visible, CPU always in the range 2%-%5, GPU fluctuating around 2%, is by a large margin the most demanding app. I have an external UHD monitor but I don't observe any significative difference regarding displays. I any case, there should be almost no activity when Zotero is out of sight, not indexing and not syncing. As its current consumption, it's not an app I would keep running in the background on battery.
  • I kept observing the background behavior of Zotero. Eventually it recedes a bit but one thing is notorious: it's the only background app which %GPU doesn't eventually goes down to 0, instead Zotero stays at 0.1% all the time (except for some very isolated fluctuation), this is a low number but still weird and may be indicative of some issue. Regarding %CPU in background again is not high but neither it is low, Zotero easily remains in the top-5 with usage 1% and 2% (actually higher numbers that the Zotero 6 on Intel, or every other Intel app which all tend to keep around 1% on background).
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