Your PureCoverage instrumented program should typically run 1.5 to 3 times slower than your non-instrumented program.
Code compiled with debugging data (-g) runs more slowly than code without, because PureCoverage adds many additional counters to note line coverage data.
When the program exits and saves data, additional overhead is incurred, roughly proportional to the size of the program. To minimize this overhead, exclude libraries such as libc, libC, libX, and libm from coverage.
The data from these libraries is not likely to be useful, and the time taken to save coverage data for all the unused code in the library may be substantial. This is particularly important when the libraries are shared libraries, and all functions in the library are present, not just the ones your application requires.
Note:
The overhead when using Purify and PureCoverage is less than the combined overhead for using these products separately.