Geoff_S, it looks like another process running in background or a file/directory permission problem is the cause of long startup time of UltraEdit on your machine.
I suggest to click in Windows Task Manager on tab Startup, uncheck all items, restart Windows and check if UltraEdit starts now within 2 seconds (on opening just 1 file and not 100 files). Find out via re-enabling items again on Startup tab of Windows Task Manager which application/process is responsible for the delays on starting UltraEdit and opening files. Usually the list of applications started on start of Windows contains about 50% applications which the user will not miss when not being started automatically.
In case of file/directory permissions is the cause of long delays on starting UltraEdit, use the filer options of Process Monitor. The toolbar of Process Monitor contains on right side 5 symbols to enable/disable global filters. I suggest to toggle off all filters except Show File System Activity (filing cabinet symbol).
Next right click on columns header line of Process Monitor, left click on Select Columns and enable Duration. The Duration column is added as last column. Click with left mouse button on column header, hold left mouse button and drag the column to the left, for example between Date & Time and Process Name. You might need to do this in two steps depending on width of columns and width of Process Monitor window (screen width). This column displays the time needed for each logged action in seconds with a microseconds resolution.
Clear the current log with Ctrl+X, start UltraEdit, switch back to Process Monitor and stop capturing with Ctrl+E. Next press Ctrl+S, select Events displayed using current filter and uncheck Also include profiling events and select as format Comma-Separated Values (CSV). Then save the record. Start a spreadsheet application like Excel or Calc and load the UTF-8 with BOM encoded CSV file using comma as separator. Sort the rows in the spreadsheet application by Duration column. Now you should easily see what causes the long delays and look in Process Monitor with lines sorted as recorded what are the file system activities around the ones needing long time to finish.
Of course it is also possible to open the CSV file in UltraEdit, convert the CSV file to fixed width and sort the lines in now fixed width file according to columns of Duration. So you don't need a spreadsheet application installed at all to analyze the log of Process Monitor.