I haven't heard of this for a very long time but about 10-12 years ago I had the same problem. After searching I found that it was related to samba mounts slowing things down.
I never used or needed samba but nevertheless when I made the changes shown below opening speed of thunar was back to normal.
Give it a try. If it makes no difference you can either leave the edits or restore the original.
Edit /usr/share/gvfs/mounts/network.mount and change it from:
Code:
[Mount]
Type=network
Exec=/usr/lib/gvfs/gvfsd-network
AutoMount=true
to
Code:
[Mount]
Type=network
Exec=/usr/lib/gvfs/gvfsd-network
AutoMount=false
it will make opening up thunar very quick again even for the first time. If you want the smb browsing you just click on the network:/// link in thunar and it will then do the browsing search which takes a bit of time.
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