I found also something interesting:

"Pre#{i.to_s}Post" seams to me cheaper than 'Pre'<<i.to_s<<'Post'

although ruby has to parse the double quoted string?

bye!
Dominik


> Often '<<' is fast, but not always.
>
> In one application, where I was generating a CVS file from a largish SQL 
> result set, I made the program over 100 times faster by changing
>
> result = ""
> for r in results
> csv_string = to_csv(r)
> result << csv_string
> end
>
> to
>
> result = []
> for r in results
> csv_string = to_csv(r)
> result << csv_string
> end
> result = result.join