Setup the build directory with gprof flags

 meson setup build -Dc_args="-pg" -Dc_link_args="-pg"

Compile the project

 meson compile -C build

Run the testcase to generate 'gmon.out'

 ./build/thunar/thunar

Analyze with gprof

 gprof ./build/thunar/thunar gmon.out > analysis.txt