Steve,

Let me answer your question from a different angle.
If your goal is to make sure that use a unique file name, try using
sys(2015) as in

local lcfilename
m.lcfilename = sys(2015)
*create the file 
if file(m.lcfilename) ;
then 
   * do something
else 
   * do something else 
endif 

hope this helps.

In my experience, file() function is pretty fast on local drive. Now if have included a path in the parameter of the function, which has a newwork drive, it may take longer, especially when the connection to that drive hasn't been active for some time.

Dawa