@shaknais Synchronised extra work in the start of ANY minute, as fired off by EVERY cron on the planet, will add to *this* problem. Cron (as I have ever used) does not add jitter to its wakeup on the minute, whichever minute that is. (Picking random minutes does reduce *other* problems.)
To be clear: 1/60Hz spikes are independent of 1/3600Hz spikes etc: they should both be dealt with, but have to dealt with separately.