edit:
stress --vm-bytes $(awk '/MemAvailable/{printf "%d\n", $2 \* 0.12;}' < /proc/meminfo)k --vm-keep -m 1
ORPort 9001 Nickname foobar AccountingMax 512 GB AccountingStart week 1 00:00 DirPort 9030 ExitPolicy reject *:*
edit:
And limit CPU use using cpulimit.