You could load the hash table when mIRC starts, but then the table won't reflect any changes made to the file between runs of the alias.
Of course, you could add/remove from the hash table when you add/remove from the ini file, or work with just the hash table, using the ini file only on start & on exit/disconnect.
Technically you could do it using just the ini file, but the process of searching the file would take a lot longer, especially if you hae a large ini file.
