Add to the script to be profiled:

Start:

PS4=$'\\\011%D{%s%6.}\011%x\011%I\011%N\011%e\011'
exec 3>&2 2>/tmp/zshstart.$$.log
setopt xtrace prompt_subst

End:

unsetopt xtrace
exec 2>&3 3>&-

Compile and run the processor:

make
./log2callgrind < /tmp/zshstart.6560.log > zsh.callgrind

View the result:

kcachegrind zsh.callgrind

Limitations:

• This approach is utterly broken when there is any parallellism. You'll have to fall back to zprof when that is the case.
• It seems kcachegrind doesn't like it when you use the same filename for different traces.. careful.