User`s manual

Preference variables located in INI and MPF files
A-270 ModelSim Variables ModelSim Xilinx User’s Manual
Opening VHDL files
You can delay the opening of VHDL files with a entry in the INI file if you wish.
Normally VHDL files are opened when the file declaration is elaborated. If the
DelayFileOpen option is enabled, then the file is not opened until the first read or
write to that file.
[vsim]
DelayFileOpen = 1