I did some benchmarking earlier in the week for the new patch which was just commited to allow formatting in the log_line_prefix string. In version 0.4 of the patch there was some performance regression as I was doing appendStringInfo(buf, "%*s", padding, variable); instead of appendStringInfoString(buf, variable); This regression was fixed in a later version of the patch by only using appendStringInfo when the padding was 0.
I've attached a the cleanup patch for this. This one just converts instances of appendStringInfo into appendStringInfoString where appendStringInfo does no formatting or just has the format "%s".
