They are certainly going to be less expensive that actual
filesystem operations that hit the physical disk, but it will
still be an unwanted overhead in 99.9% of cases.
In any case, the overhead is only one issue.
Seriously, checking the file path string *length* is above 260
characters to see if it needs to be fixed is not what I call an
overhead.
And IF the path is indeed too long, IN THOSE CASES personally I'd
prefer that the D standard library fixes the path in order to
make the disk/file operation succeed, than having my application
crash, because I didn't know I had to put a "version ( Windows )"
fix somewhere in my code.
But hey, I may be wrong, software robustness and stability is
often much overrated... ;)
