Thanks. I'm willing to try whatever it takes but not knowing Docker at all, I'm afraid it will be complicated for me to install the Joplin Server on my NAS. But if it can solve my slowness problems then it might be worth it. On the other hand, I don't know how to go about duplicating my profile, a simple copy and paste, a backup restoration, an export import?
I'm so disappointed, everything was going so well before activating the sync Since then, Joplin has been unusable for me and I wonder if I will be able to continue using it
Actually I just saw you have nearly 4000 tags and there's a well known performance issue for users who have many tags. So in the end I don't think it's related to sync - it's just that while sync is in progress, the tag list is being constantly updated which probably freezes the UI.
It's an issue we want to address and some work is being done for this, but not sure when it will be ready unfortunately.
I don't assume that collapsing the tag list helps? (if you click on the "TAG" header in the sidebar)
Ok, I'm a little reassured to know that this may be linked to a known issue. This will perhaps save me from having to divide my data into two profiles as I envisioned. Is there a link so I can follow it and be informed?
I tried to collapse the list of tags, it might be a little better but I'm not sure. I'll leave it folded just in case.
Meanwhile, the setting synchro target:none allows me to use Joplin in good conditions, then I put WebDAV back on when I am not using my computer, fortunately there is this setting
When I click on synchronize myself, it launches the "big" synchronization (I'm starting to understand ;)), and the "Downloaded" message which continues. There, Joplin is even slower than with the "small" automatic synchro:
I would restart the big sync when leaving my computer. I hope these "Downloaded" are part of the end of the initial sync and that there will not be this at each subsequent sync.
35 hours later, and this last step (I hope ;)) of verification is still in progress:
The sync status shows small differences between what is synced and the total:
Is the fact that this "verification" takes so long normal, or is it my "problem" with a large number of labels which slows down this step as well, or something else?
In the meantime, I took a look at Joplin Server, but my Synology DS118 NAS is not officially compatible (the Container Manager packet necessary for installing Docker is not available for this model). It must not be powerful enough (ARM 4-core 1.4 GHz Realtek RTD1296 CPU and 1G RAM). There is an unofficial solution here but since my NAS is not very powerful, the fact that I will only sync 2 or 3 devices on my LAN, and given the complexity of installation compared to Synology WebDAV Server (installed in a few clicks), I don't think it's worth it for me and my usage. Otherwise, I thought about installing it on my Windows PC which is on 24 hours a day but that also seems complicated to me...
Well it's mostly the app problem since it's due to that performance issue I mentioned earlier, which means the sidebar (and all its tags) is being unnecessarily reloaded every time an item is being downloaded.
It would be great if this issue is fixed with this update. And if I understood correctly this could also solve my lag problems during "small" syncs as well as other performance problems. I'm impatient to try it, thank you very much to you and the programmer who worked on this pull request
I currently have Joplin in version 2.14.20. Do you know when this fix will be available and if I just need to check for updates via Help: Check for updates?
It would actually be part of v3, but you can already download it if you enable pre-releases as described here. Pre-releases are generally safe to use and in your case it sounds like it could be worth it.
I will now be able to start syncing my second device, another Windows PC, with 3.0.6 version of course .
I always ask myself a little question about WebDAV path ending, I wonder if I should put a / or not, or whatever? http://192.168.1.26:5005/joplin/
or http://192.168.1.26:5005/joplin
If yes, I tell myself that Joplin Android may be unusable. Is it still worth trying to synchronize my mobile Android or is it not even worth it?
What do you recommend to me @laurent and @personalizedrefriger ?
Since then, Joplin has been unusable for me and I wonder if I will be able to continue using it 
It's been "downloading" for about 20 hours now (and Joplin is unusable during this process):
