http://www.erlang.org/doc/efficiency_guide/profiling.html 11.4  Tools fprof fprof measures the execution time for each function, both own time, that is, how much time a function has used for its own execution, and accumulated time, that is, including called functions. The values are displayed per process. You also get to know how many times each function has been called. fprof is based on trace to file to minimize runtime performance impact. Using fprof is just a matter of calling a few library functions, see the fprof manual page in tools .fprof was introduced in R8. eprof eprof is based on the Erlang trace_info BIFs. eprof shows how much time has been used by each process, and in which function calls this time has been spent. Time is shown as percentage of total time and absolute time. For more information, see the eprof manual page in tools. cover The primary use of cover is coverage analysis to verify test cases, making sure that all relevant code is covered. cover counts how many times each executable line of code is executed when a program is run, on a per module basis. Clearly, this information can be used to determine what code is run very frequently and can therefore be subject for optimization. Using cover is just a matter of calling a few library functions, see the cover manual page in tools. cprof cprof is something in between fprof and cover regarding features. It counts how many times each function is called when the program is run, on a per module basis. cprof has a low performance degradation effect (compared with fprof) and does not need to recompile any modules to profile (compared with cover). For more information, see the cprof manual page in tools.