I have several files that are about 1.2 and 2.4 megabytes in size. I suddenly experienced massive slowdowns on them recently when trying to open or save them and would like to know how big files have to be before they cause significant slowdowns, to rule out the possibility that their size is the culprit.

Those files are a bit big, but if the slowdown was sudden onset, it might  be something other than sheer size.

I'd try:

• File>clean document... many unused defs can slow down a file
• Clear and shorten the recently used list in the preferences>interface
• Check for any blurs or filters accidentally applied. Filters and blurs are rendered on the fly (as all svgs are) and can hammer processors.

Feel free to share an example file for examination.

Here some steps you can try to take in order to potentially reduce CPU/RAM usage:

• Hiding layers not currently in use.
• Change display mode to "outline".
• If using imported raster images, the Image Rendering mode can be set to "Blocky (optimizeSpeed)".

I've attached one of the files. There are only very small slowdowns when I edit the file itself, but when I save or open it, it can take several minutes (sometimes 10 or 15 minutes) to do so.

I've noticed that "ZpQaa0q" was appended to the end of the file name when I uploaded it. I assume nothing else has changed.

Thanks for the tips!

[Moderator edit: switched the image to attachment mode to load the page faster.]

Oh, I just noticed I saved it in gallery mode instead of attachment mode, and it's not showing for me. I'm trying to attach it in attachment mode now.

@apmbcn If a 1 or 2 MB file size is a "bit big" my typical 700 MB drawings are astronomical.  Yes, I get the same issue you are having.  My hang time can stretch to an hour to open or close a file.  Like you, I do not hang while working in the file - unless I am doing anything with text.  While working - my fan gets tested to its limits.

The issue is not you, your work process, or your technology.  Spending thousands of dollars to upgrade will do nothing for you.

RAM use does not turn the fan on.  Poor CPU utilization is the problem.  The coding is bad and needs to be overhauled.  RAM is irrelevant. 

Notice that I can open the same sag file [ 700 MB ] on the same machine with blender in less than a minute !

Notice also that a 1 MB file is considered big in the terabyte era !  RIDICULOUS !

The problem is that inkscape was created during the kilobyte era for people who wanted to create a logo only a few pixels in dimension.  It is far easier to create a web page layout in inkscape than it is to manually enter grid point data in a content style sheet.  Inkscape is basically WIX's grandfather as a layout tool.

Today, we who draw professionally, try to rely on inkscape for functionality it really does not have.  It might still be useful for small icon design - but that is waning.  The management of the project - french academics - have little interest in fixing this problem.  You can search the web and you will find complaints about it dating back at least a decade.

The best work method one can adopt to deal with this problem is to walk into your studio - tell the computer to open your day's files - go make some coffee - - - close everything as you drop your blinds on the way out at night.

OR - repair the code.

This took about 35 seconds to load on my i7 on ubuntu 20.10 with Inkscape 1.1

There's lots of stuff off canvas which may be affecting the load time. 

I would simply copy and paste the things you need to a new file, save and the open that.

I've attached an image of what I can see.

@apmbcn May I ask what your work style is?  Do you use inkscape like I do - dedicated 10 hours a day almost daily leading to large items like maps - or are you an incidental user who makes small stuff now and then with reliance on inkscape only when you need that one tool?

I ask because it seems this problem gets worse with use.  RAM issues do not do that.  CPU issues -  eg pointer problems - do.  Blender solved many of these issues by relying on GPU.  

If you use it like I do, you might get better function and save time/money by using a second system.  Use one computer to do a task (eg editing) on MWF and the second system to do another task on TRS.  This would give each system time to cool and clear their processors.

Hardware seems to make a difference in this case.

• 2.8Ghz dual core, 4GB ram, 2TB HDD, Linux Mint 20: about 3min to load, 2 min to save a copy.
• 2.8Ghz 8 core, 32GB ram, 2TB SSD, Win 8.1: about 30 seconds to load, 1 min to save a copy.
• 2.8Ghz 8 core, 32GB ram, 2TB SSD, Linux Mint 20: about 10 seconds to load, 20 seconds to save a copy.