1. A control file for a program, especially a text file automatically read from each user's home directory and intended to be easily modified by the user in order to customise the program's behaviour. Used to avoid hard-coded choices (see also dot file, rc file).
2. A report on the amounts of time spent in each routine of a program, used to find and tune away the hot spots in it. This sense is often verbed. Some profiling modes report units other than time (such as call counts) and/or report at granularities other than per-routine, but the idea is similar.