here are some top shell results (write to NAS using SMB, encrypted and unencrypted datasets)
1) encrypted
top - 14:12:32 up 7 min, 1 user, load average: 1.87, 1.30, 0.70
Tasks: 232 total, 2 running, 230 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.5 us, 41.8 sy, 0.0 ni, 38.8 id, 15.0 wa, 0.0 hi, 2.8 si, 0.0 st
MiB Mem : 31770.5 total, 12106.4 free, 19502.7 used, 161.3 buff/cache
MiB Swap: 4095.9 total, 4095.9 free, 0.0 used. 11920.9 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1870 root 1 -19 0 0 0 S 33.7 0.0 0:18.45 z_wr_iss
7779 user 20 0 60512 25412 12824 S 24.7 0.1 0:24.89 smbd
7952 root 20 0 0 0 0 R 19.3 0.0 0:18.13 io_wqe_worker-0
1872 root 0 -20 0 0 0 S 13.3 0.0 0:09.77 z_wr_int
284 root 0 -20 0 0 0 S 7.7 0.0 0:02.60 spl_kmem_cache
290 root 39 19 0 0 0 S 6.0 0.0 0:05.37 dbuf_evict
283 root 0 -20 0 0 0 S 1.0 0.0 0:00.82 spl_dynamic_tas
2 root 20 0 0 0 0 S 0.7 0.0 0:01.00 kthreadd
1903 root 39 19 0 0 0 S 0.7 0.0 0:00.16 dp_sync_taskq
2331 root 20 0 419736 188964 24516 S 0.7 0.6 0:03.52 middlewared (wo
12 root 20 0 0 0 0 S 0.3 0.0 0:00.19 ksoftirqd/0
2) unencrypted
top - 14:12:32 up 7 min, 1 user, load average: 1.87, 1.30, 0.70
Tasks: 232 total, 2 running, 230 sleeping, 0 stopped, 0 zombie
%Cpu(s): 1.5 us, 41.8 sy, 0.0 ni, 38.8 id, 15.0 wa, 0.0 hi, 2.8 si, 0.0 st
top - 14:14:09 up 8 min, 1 user, load average: 2.25, 1.62, 0.88
Tasks: 235 total, 6 running, 229 sleeping, 0 stopped, 0 zombie
%Cpu(s): 4.0 us, 50.1 sy, 0.0 ni, 31.6 id, 8.8 wa, 0.0 hi, 5.6 si, 0.0 st
MiB Mem : 31770.5 total, 23429.4 free, 8179.2 used, 161.8 buff/cache
MiB Swap: 4095.9 total, 4095.9 free, 0.0 used. 23244.2 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7779 user 20 0 59488 24372 12840 R 53.9 0.1 0:39.41 smbd
7952 root 20 0 0 0 0 R 44.1 0.0 0:28.63 io_wqe_worker-0
1870 root 1 -19 0 0 0 S 28.3 0.0 0:29.41 z_wr_iss
1872 root 0 -20 0 0 0 S 15.8 0.0 0:15.61 z_wr_int
284 root 0 -20 0 0 0 S 12.2 0.0 0:04.26 spl_kmem_cache
290 root 39 19 0 0 0 R 5.6 0.0 0:08.73 dbuf_evict
626 root 20 0 2712588 261908 26004 S 3.9 0.8 0:25.84 asyncio_loop
4461 root 20 0 419644 191824 27532 S 1.3 0.6 0:03.77 middlewared (wo
2 root 20 0 0 0 0 S 1.0 0.0 0:01.60 kthreadd