I should probably weigh in here and say my mIRC is installed to the mechanical hard drive on this laptop rather than the SSD (I use the SSD as little as possible), and that the settings are within the mIRC folder itself rather than using AppData, 'cause I personally found it annoying to access stuff.
Don't know if this information will have any impact on the tests you conducted, though.
Still, the mode2 result looks very promising.
