For that same reason, several people wondered why I did not like widestring. The main reason why I recommend not to use widestring is this one:
// approx. 25 million iterations per second
for i:=0 to 100000000 do begin
// approx. 0.0055 million iterations per second
for i:=0 to 100000 do begin
Note, how widestring is extremely slow for this specific test. This is the kind of stuff that can make a well made application perform really bad. A TCP/IP ping request between two servers on a good network uses less time than it takes to add a space to a widestring on my reasonably fast laptop.