I ran three trials of each on a min spec 2019 MacBook Pro 16". All numbers are ms rounded to the nearest integer, all browsers are latest stable. I also loaded the page with dev tools closed since that affected times.

Browser: (trial 1 prep, trial 1 chart), (trial 2 prep, trial 2 chart), (trial 3 prep, trial 3 chart)

Chrome: (649, 347), (638, 343), (618, 358)

Firefox: (353, 307), (358, 307), (361, 308)

Safari: (281, 264), (287, 258), (309, 262)