Slow change detection on Mac client

Hi everyone
Our organization recently got a NextCloud setup and I have been trying to synch my current project data from my MacBook to the cloud to ease the transition from development to computing on our server farm.

I am using the Mac desktop client version 2.5.1final (build 20181204).

I am trying sync one directory $HOME/Nextcloud with the following contents: 1,253,949 files in 188,754 folders for a total of 665 GByte. Some files are large (up to several GByte), but the majority are smalle (e.g. log files from computational experiments etc.).

The syncing itself seems to works fine once local change detection has been run, but I only got there once! It takes several hours (definitely more than 2) for the local change detection. That is, unless the machine is online and running for at least several hours, syncing does not even start.

I have mounted my remote nextcloud folder using CIFS and am in the process of copying the data manually. BUT, after I finish the initial upload, the local change detection will still mean that I will rarely be able to sync with the cloud.

Is there any way to speed up local change detection with the Mac client? Otherwise, I cannot really use the client and will need to sync in another way e.g. using CIFS and rsync. That would kind of defeat the purpose, though.

Thanks in advance for any help, support, or pointers you can provide!

Best,
Peter

P.S.: There is a similar topic from April 2018, but it is a small number of files and an even slower change detection. So I do not think that this is relevant.