PDF reader very slow, any way to speed things up?

alexcr87

I only have two PDFs open right now and switching between them is quite slow (has been for some time). I also notice that some figures take an extraordinary amount of time to render (~30-60 seconds after page load). Scrolling and zooming also lag frequently when reading papers. I really like Zotero and the new integrated reader but it’s painful to use.

Is there any way/any setting to make the reader perform better? I have a 2020 quad core macbook pro with 16GB RAM so I don’t think that’s the issue.

dstillman

That sounds like a problem with those specific PDFs (e.g., if they have huge scanned images) — that's obviously not normal performance with the PDF reader or no one would use it (and we wouldn't have released it). Zotero 7 next year will improve performance dramatically, including in the PDF reader, but the current reader should be perfectly usable for the vast majority of PDFs.

Can you email those files to support@zotero.org with a link to this thread?

hu-itanu

I experience the same problem for many older books that are only text but that have been scanned in color or even grayscale, even if the resolution is no more than 300 dpi. If I whiten the background or convert the pdf to black and white, the reader works much faster.

alexcr87

@dstillman yes sending the PDF now, it’s not a scanned image it’s a figure with a lot of curves

understood about performance, i’ll wait for Zotero 7 and see how it goes

Thank you!

peterb12

I want to leap in here and say that I am seeing this too.

I am absolutely seeing the built-in Zotero PDF reader being an order of magnitude slower than either Preview.app (on Mac) or DevonThink's built-in PDF reader, on specific PDFs (that do, in fact, have lots of scanned images).

This is made more frustrating by the lack of a good UI to easily open PDFs in an external reader. For most PDFs, I'd prefer to read them in Zotero's reader! But for the slow ones, I either need to change my reader for all files, or choose "Show File" and navigate there from my computer's Finder. A right click -> "Open With External Reader" option would go a long way towards making this less burdensome.

I will send a sample file to support as mentioned above.

adamsmith

This is made more frustrating by the lack of a good UI to easily open PDFs in an external reader.

There's an add-on for that: https://github.com/retorquere/zotero-open-pdf

peterb12

Great suggestion, thanks. .

dstillman

@peterb12: Probably not much we can do about that. That file is entirely made up of huge scanned images, and it performs incredibly poorly in both Firefox and Chrome, even on a recent Apple Silicon Mac. Zotero's PDF reader is based on the Firefox PDF reader, so the performance there is roughly what you should expect to see in Zotero 7 next year. (Zotero 6 is based on an older version of Firefox, uses a much older pdf.js, and isn't native on Apple Silicon.)

Unfortunately this is a situation where Preview is just going to outperform pretty much anything. If even the main browsers can't handle a given file well, I'm afraid we're just not going to be able to do much better. You might be able to reprocess the file at a lower resolution or lower compression level to speed it up.

nhan000

Really look forward to Zotero 7 PDF reader. I'm annotating densely a few textbooks with 300-500 pages and the performance leave a lot to be desired: annotation takes 2-3 seconds to show up), pages take some time to render when scroll, PDFs that have large size (> 400MB) can't be open.

That being said, I'm forever grateful for Zotero being so useful and that the devs always look for ways to improve it.

alexcr87

Yeah I hesitated too between the external reader/built-in reader because of performance issues but in the end having every annotation synchronized is really a big upside..

Still looking forward to Zotero 7 too though, lots of big textbooks here too ;-)

BeingAndyC

I'm finding Zotero 6 to be almost unusable on Mac. I have an M1 MacBook Pro beast, and everything takes several seconds to do in Zotero, from the library to the reader. I wish the folks behind Zotero would just come out and say its slow but they're working on it. Right now, I feel like I'm being gaslit about the performance.

dstillman

@BeingAndyC: If you're experiencing a problem, just report it — don't assume your experience is universal. Millions of people use Zotero, and it's obviously not "almost unusable" for everyone on a Mac. Zotero is largely developed on Apple Silicon Macs, and performance on Apple Silicon Macs should be totally normal — and, in fact, faster than it's ever been. If that's not what you're seeing, something is wrong on your system.

The thread above is about PDFs with massive scanned images that are, in fact, almost unusable in the PDF readers of both Chrome and Firefox — Preview is the exception there. If that's what you're referring to, you'll see the same thing in Zotero, and without reprocessing the PDFs it will likely only get as good as current Firefox in Zotero 7. If something else, start a new thread and provide Debug IDs for specific operations that are slow.

BeingAndyC

You're right! As a test, I installed Zotero on a second computer, and it works as you say. I've started a new thread as you suggested for the original computer. Thanks!