it depends what you mean
if you talk about Pharo code then those tools should be enough , unless it freezes Pharo (a 100% consumption does not necessarily imply a freeze)
if you talk about the Pharo VM itself then you will need to use one of the countless profilers that exist for C/C++ . Some OSes come included with them. MacOS which what I am using can sample a running process and tell you exactly which function/method consumes how much CPU.��
Obviously more specialised tools can be even more of an assistance like Valgrind
But then it will require knowledge of the Pharo VM internals.
if it freezes pharo and you know its pharo code then its a matter of taking a look at changes file and testing on a new image one change at the time until you identify the code that causes the slow down.��
At least that is what I have done one time I really messed up Morphic draw loop and froze my image.��