Unfortunately there is no really fast way of doing this. If you really need performance, then the only way to make it a significantly faster is to work with NoteCollection- Class and get all folders. Then run through the NotesDocuments representing the folders and read the item "$Title". Here is example code of doing this:
NoteCollection nc = database.createNoteCollection(false);
nc.setSelectFolders(true);
nc.buildCollection();
String id = nc.getFirstNoteID();
while (id.length() > 0) {
String strFolderName = ""
Document docFolder = database.getDocumentByID(strFolderId);
strFolderName = docFolder.getItemValueString("$Title");
if (strFolderName.startsWith(prefix)) {
....
}
}
In my tests this was factor 2-3 faster than using the getViews()- method.