Lightroom Classic hangs on startup when using NAS across two computers

Hi. I’m trying to work with Lightroom Classic on two computers - a Windows PC (my main machine) and a MacBook. All my photos are stored on a Synology NAS, which I access via SMB. However, I keep separate catalogs locally on each computer.

The problem is that as soon as I import into the Mac any photos that were previously imported on Windows, Lightroom on Windows becomes extremely slow to start. The next time I try to launch it, nothing happens sometimes even for up to 30 minutes. It’s a lottery, sometimes it starts in 1 minute, sometimes 15 or 30. The process appears in task manager and I can see that it heavily uses the network connection to the NAS. I can also hear the NAS drives working intensively, so Lightroom is clearly reading a lot of data.

Why is this happening and how can I fix that? Why is it a problem if catalogs are separate and only source files are shared?

It also has trouble reading and writing metadata to TIFF files. Sometimes it shows that metadata has been changed and asks whether I want to import or overwrite it, but often neither option works.

At the moment, this issue makes it practically impossible to work with Lightroom across two computers, because I can’t afford to wait half an hour every time it starts.