FunctionProfiler

If you're not an addon developer, you may be looking for Addon Profiler - CPU Usage instead

/fp, /functionprofiler or click the minimap button to toggle the UI

Profiling is disabled by default on login, and enabling profiling will have a minor performance impact.

Basic usage:

if NumyFunctionProfiler then
    -- wrap all functions in self
    NumyFunctionProfiler:WrapModules('OwnerName', 'ModuleName', self);
    -- wrap only self.functionName
    NumyFunctionProfiler:WrapInPlace('OwnerName', 'ModuleName', self, 'functionName');
    -- wrap a single function, useful for e.g. local functions
    someLocalFunction = NumyFunctionProfiler:Wrap('OwnerName', 'ModuleName', 'someLocalFunction', someLocalFunction);
    -- wrap all functions in self and 1 layer of down (e.g. self.SomeModule.SomeFunction)
    NumyFunctionProfiler:WrapModules('OwnerName', 'ModuleName', self, 2);
end

Special thanks to i_lightspark for the initial snippet that this project was based on (with their blessing 💙)