std::vector is smaller

e.g.

before

peak heap memory consumption:
528,0MB after 20.266s
peak RSS (including heaptrack overhead):
831,9MB
total memory leaked:
2,0MB (392,7kB suppressed)

now

peak heap memory consumption:
512,0MB after 20.608s
peak RSS (including heaptrack overhead):
804,8MB
total memory leaked:
2,0MB (392,7kB suppressed)