Zotero Performance Issues: Persistent Loading and Lag

Ted.Lee

Zotero ID: 1502124355

**Issue Description:**
I’ve been experiencing intermittent performance issues with Zotero, where it becomes slow and unresponsive, often stuck on "Loading..." indefinitely. This happens even after I’ve disabled all plugins, which was one of the initial troubleshooting steps I took. Additionally, I’ve already disabled automatic syncing based on online recommendations, but the problem persists.

My Zotero library is stored entirely in the cloud, and I’m wondering if the size or volume of my cloud-stored files could be contributing to the lag. Could this be a potential cause?

**Steps Taken So Far:**​

Disabled all plugins.
Turned off automatic syncing.

**Questions:**​

What could be causing Zotero to remain stuck on "Loading..." even after disabling plugins and syncing?
Could the size or number of files stored in the cloud be a factor in the performance issues?
Are there any other troubleshooting steps or settings I should try?

Any insights or suggestions would be greatly appreciated!
  • adamsmith
    What do you mean by "My Zotero library is stored entirely in the cloud"? Just that you're syncing with Zotero?
  • Ted.Lee
    Yes, that's exactly what I meant. I am syncing through Zotero.
  • dstillman
    Can you provide a Debug ID for Zotero startup, using the "Restart with Logging Enabled…" option?
  • Ted.Lee
    The ID is 436135712. Thank you very much for your patience and help!
  • adamsmith
    (That looks like a report ID, not a debug ID -- "Debug ID" in dstillman's post is linked to instructions)
  • Ted.Lee
    I’m sorry, I mixed them up. The Debug ID is D91507671.
  • dstillman
    That's not a Debug ID for Zotero startup.
  • Ted.Lee
    I actually tried to follow your advice and provide a Debug ID for Zotero startup, but then I couldn't even restart Zotero. Later, I tried downgrading to an earlier version of Zotero7, and found that those problems were resolved. So, these issues might be due to incompatibility between the latest version and my computer. Thank you again for your help.
  • dstillman
    That's very unlikely, and if it is the case we're want to determine that for sure. You should reinstall the latest version and provide a Debug ID. If "Restart with Logging Enabled…" isn't working for some reason, see Reporting Startup Errors.
  • Ted.Lee
    To solve this problem, I reinstalled the latest version of Zotero, but strangely, there have been no issues so far. In this case, should I wait until a problem occurs before reporting it?
  • dstillman
    Yes.
  • Ted.Lee
    Report ID in "Report errors": 145042151
    Debug ID: D344511950

    Hello, the issue has occurred again! After opening Zotero, I cannot load the files under the folders. This time, I will try to provide screenshots to explain the situation I encountered, hoping to make it clearer.

    1. The issue I encountered – the relevant screenshots are attached below.
    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/9jngroboh7b3vy5yfein.png

    2. Actions I've tried so far:

    1) Disabled all plugins.

    2) Submitted an error report via "Report errors", with report ID 145042151.

    3) I clicked "Restart with Logging Enabled...", but Zotero didn’t automatically restart (I'm not sure if that's normal), so I manually reopened Zotero. I found that 1512 lines were logged, so I submitted the output. The debug ID is D344511950.
    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/gf3cb1665earj1jwrfby.png


    Please let me know if this information is sufficient, and if there’s anything more I can do to help you understand the problem I’m facing. Thanks for your help!
  • Ted.Lee
    I would like to add one more issue: After reopening Zotero, I found that I cannot right-click on entries or double-click to open the items. However, I can open them by clicking on the PDF attachment. The Debug ID is D189315319.
    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/0ubt2id15yh97foxa1yb.png
  • dstillman
    edited March 6, 2025
    What kind of disk is D:?

    How big is the zotero.sqlite file in your data directory?

    If it's an option, I'd be curious how much faster this is if you moved the data directory back to the default location on your main disk (assuming it's an SSD and D: is not). If you move the data directory back to C:\Users\[user]\Zotero (so that C:\Users\[user]\Zotero\zotero.sqlite exists) with Zotero closed, it should prompt you to use that folder when it starts up.
  • Ted.Lee
    I’ve divided my computer’s SSD into several partitions, and D: is a separate partition I created from C: to store research data. Should I move it back to C:?

    As for the zotero.sqlite file, it’s 2.32 GB. Is that too large? Should I clear some of the previously viewed references (if possible, it would be better not to delete them)
  • dstillman
    edited March 6, 2025
    OK, if D: is still the SSD, that's fine.

    Don't delete anything or make any changes we don't recommend while we're debugging this.

    Do you subscribe to some heavy-volume feeds using the built-in feed reader?

    If you download https://sqlitebrowser.org/, open zotero.sqlite in that, and run VACUUM, does that reduce the size of the file? (That might take a while to run, and Zotero will need to be closed.) Let us know how long that takes and the size of the file after vacuuming, and whether that makes a difference to the startup speed.

    https://stackoverflow.com/questions/18126997/how-to-vacuum-sqlite-database/76826970#76826970
  • Ted.Lee
    Thank you! I’ll follow your suggested steps and try them out. If there’s any update, I’ll post it in the forum to keep you informed.
  • Ted.Lee
    Hello, I tried running VACUUM to reduce the size of the file, and after compression, it shows 2.16 GB. After the compression, I did notice that the startup speed is indeed faster!

    Additionally, I do subscribe to some heavy-volume feeds. Is this the main reason why Zotero is starting slowly? If so, I can unsubscribe from these feeds.
  • dstillman
    Could you run these three separate statements in DB Browser and let us know the output?

    SELECT COUNT(*) FROM itemDataValues;

    SELECT COUNT(*) FROM items JOIN libraries USING (libraryID) WHERE type!='feed';

    SELECT COUNT(*) FROM items JOIN libraries USING (libraryID) WHERE type='feed';
  • Ted.Lee
    edited March 6, 2025
    I’ve already executed the code, and here are the relevant results:

    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/9pj11iggpngxczgroy61.png

    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/30ozwp4hx2blelnfm9nr.png

    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/haidb86m5dholq3ux39a.png
  • dstillman
    edited March 7, 2025
    And are you currently having this problem when you open Zotero?

    If not, and you go to Tools → Developer → Run JavaScript and run the following command, does it happen again on the next startup?

    Zotero.Prefs.set('purge.items', true)

    (If it does, you can fix it by force-quitting Zotero, going to the Zotero profile folder, opening prefs.js in a text editor (e.g., Notepad), and deleting the extensions.zotero.purge.items line.)
  • Ted.Lee
    At first, I tried running Zotero.Prefs.set('purge.items', true) in JavaScript, but it didn’t execute successfully. Then, when I tried reopening Zotero, the issue still persisted.
    https://s3.amazonaws.com/zotero.org/images/forums/u8708602/babb8c5sibq2yvdn36bw.png

    So, I force-closed Zotero, found prefs.js, and followed the recommendation to delete the extensions.zotero.purge.items line. After that, Zotero opened normally!

    Does this mean the issue is now resolved, and I don’t need to unsubscribe from my feeds or delete any of my files? (I’ve been using Zotero for many years and have indeed accumulated a lot of data.)
  • dstillman
    edited March 7, 2025
    No, it executed successfully. ("undefined" is correct there.) So you're still seeing the problem. And no, it's not resolved — it will recur at startup after the next time you empty the trash or old feed items are automatically cleaned up.

    Basically, after items (including feed items) are deleted permanently, Zotero does some cleanup at the next startup, and that's taking a very long time for you and a few other users. This is probably a result of subscribing to some high-volume feeds, but it shouldn't happen and is likely some sort of optimization bug in the database software we use. (I suspect this could be reproduced within SQLite Browser itself.) Deleting items or unsubscribing from feeds won't help at this point.

    If you don't mind sharing the database privately with us, could you ZIP the zotero.sqlite file, upload it somewhere (Google Drive, Dropbox, etc.), and send a share link to support@zotero.org? That would let us run some tests to see if we can get the cleanup process to run more quickly on a database the size of yours.

    Alternatively, you could export just the itemData and itemDataValues tables to CSV and send us a ZIP of those, and we could see if we could reproduce this with a recreated database with just those tables, but I don't know if we'll see the same behavior. But we can certainly try that first.
  • Ted.Lee
    I’m willing to upload the files to help resolve this issue. However, I have other work to handle today, so I’ll take the next couple of days to decide on the best way to send them to you. Thank you for your support!
  • dstillman
    Thanks for sending the file — it was incredibly helpful. We were able to identify the issue and put a fix in place in the latest Zotero beta. If you don't mind, install the beta, delete any item from the trash (or go back to Config Editor in the Advanced pane of the settings and set extensions.zotero.purge.items to true), and then restart Zotero. It should then perform the cleanup process it was trying to do before, but hopefully much more quickly. Let us know if that works and how big your database file is after.
  • Ted.Lee
    Hello, and thank you for your attention to my issue and needs, as well as the efforts you've made to resolve them. I just downloaded the latest Zotero beta, deleted items from the trash, and Zotero is now running smoothly. The software opens much faster than before. What's even more amazing is that the size of the zotero.sqlite file has decreased from 2.3GB to 361MB—success!

    Once again, thank you so much.
  • dstillman
    This fix is now available in Zotero 7.0.14, so you can switch back to the release version from the download page if you don't want to stay on the beta.
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