É a opção "verbose" que pode ser definida na inicialização:
-V[N] Verbose. Sets the 'verbose' option to [N] (default: 10).
Messages will be given for each file that is ":source"d and
for reading or writing a viminfo file. Can be used to find
out what is happening upon startup and exit. {not in Vi}
Example: >
vim -V8 foobar
-V[N]{filename}
Like -V and set 'verbosefile' to {filename}. The result is
that messages are not displayed but written to the file
{filename}. {filename} must not start with a digit.
Example: >
vim -V20vimlog foobar