I don't have any delay opening a file using an UNC path. I suggest to use Filemon
to log all file accesses while you open a file in UltraEdit with an UNC path. Maybe you can see in the log what is the reason for the delay. My experience with such delays is that a security setting is the problem.
The Explorer tab in the File Tree View shows only drives and none of the virtual folders Microsoft has defined for Windows. I use also a laptop at home, in the train to/from work and in my company. To solve the problem with mapping the network drives only when I'm in the company I use a batch file like this:
if not exist "\\computer\share\dir\file that always exist
" goto !EndMapBatch
net use drive letter
: \\computer\share /persistent:no
This batch file is executed on startup of Windows with a shortcut located in the "Startup" folder of the Windows start menu. In the properties of the shortcut I have selected to run the batch file with minimized window. Of course I can click on the shortcut to run the batch file also when I started my laptop in the company without network cable plugged and later plug it and need the network drives.
You could also configure in UEStudio a user tool with just the "net use ..." command line to map the drive from within UEStudio when you need it.