Michel wrote on May 1^st, 2020 at 8:25pm:

The speed restriction of 250/10000ft is only set during climb, it is on VNAV CLB page. When the plane reaches the desired cruice altitude, preselected on PERF or VNAV CRZ page, it changes his performance to the one entered on that page. It is part of the preflight to analyze and set the speed that you want to be set on cruise.

Not exactly, apparently when CRZ is below 10k, the plane knows to keep it at 250Kt