Looking at the reload value being set in SysTick (stm32fxx-hal) I see:
`let reload = (sysclk + TIMER_HZ / 2) / TIMER_HZ - 1;`

For TIMER_HZ 1000, this comes out at 7999.
For TIMER_HZ 1000000, this comes out at 7.

(8000000Hz sysclk)

These seem like expected values... so I'm just wondering, where could this factor 6 slow down be coming from?