Just for fun I tried that on a Pi3+ with SSD and got
a) a halt because the first [ is in the wrong place, should be 
 | filename |
[filename := UUID new asString36.
FileStream newFileNamed: filename do: [ :file | ].
[ FileStream fileNamed: filename do: [ :file | ] ] bench ]
	ensure: [ FileDirectory default deleteFileNamed: filename ].

b)  '9,710 per second. 103 microseconds per run. 1.9 % GC time.' so 1/12th the performance.

tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
"#define QUESTION ((bb) || !(bb))  - Shakespeare."