If you are using XFCE on an ubuntu-based distro (e.g. Xubuntu, Linux Mint), the thunar file browser might take a very long time to load when first run. After the first run, it will probably perform normally.
To fix I found a solution online that was very simple:
Edit /usr/share/gvfs/mounts/network.mount and change the line AutoMount from true to false.
The flipside is that network drives (e.g. samba) will not auto mount. These can be accessed with the network:/// location in the left pane.