Stuttering after 2018.08 update

Output of top while playing a video (BBC-iplayer) from NFS share).
Kodi logging is switched off now.

 top - 12:34:40 up 3 min,  2 users,  load average: 3.62, 1.70, 0.68
Tasks:  75 total,   2 running,  46 sleeping,   0 stopped,   0 zombie
%Cpu(s): 26.8 us, 58.7 sy, 11.7 ni,  0.0 id,  0.0 wa,  0.0 hi,  2.8 si,  0.0 st
KiB Mem :   360520 total,    85740 free,   101000 used,   173780 buff/cache
KiB Swap:        0 total,        0 free,        0 used.   228792 avail Mem

  PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND
  297 osmc      20   0  676348 128936  57088 S 58.7 35.8   1:59.68 kodi.bin
   73 root      20   0       0      0      0 I 10.9  0.0   0:10.76 kworker/0:3
  676 osmc      20   0    5536   3020   2448 S  4.8  0.8   0:04.09 tmux: server
  756 osmc      20   0    6444   2844   2364 R  1.9  0.8   0:01.42 top
  625 osmc      20   0   11428   3980   3240 S  1.3  1.1   0:00.84 sshd
    7 root      20   0       0      0      0 S  1.0  0.0   0:00.87 ksoftirqd/0
   51 root       1 -19       0      0      0 S  1.0  0.0   0:01.39 vchiq-slot/0
 1916 osmc      20   0    1872   1224   1072 S  1.0  0.3   0:00.03 byobu-status
    8 root      20   0       0      0      0 R  0.3  0.0   0:00.72 rcu_preempt
  155 root      20   0       0      0      0 I  0.3  0.0   0:00.20 kworker/u2:2
 1914 osmc      20   0    1872   1156   1084 S  0.3  0.3   0:00.01 sh
    1 root      20   0   26884   6028   4996 S  0.0  1.7   0:02.80 systemd
    2 root      20   0       0      0      0 S  0.0  0.0   0:00.00 kthreadd
    3 root      20   0       0      0      0 I  0.0  0.0   0:00.00 kworker/0:0
    4 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 kworker/0:0H
    5 root      20   0       0      0      0 I  0.0  0.0   0:00.00 kworker/u2:0
    6 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 mm_percpu_wq
    9 root      20   0       0      0      0 I  0.0  0.0   0:00.00 rcu_sched
   10 root      20   0       0      0      0 I  0.0  0.0   0:00.00 rcu_bh
   11 root      20   0       0      0      0 S  0.0  0.0   0:00.01 kdevtmpfs
   12 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 netns
   13 root      20   0       0      0      0 I  0.0  0.0   0:00.17 kworker/0:1
   14 root      20   0       0      0      0 S  0.0  0.0   0:00.00 khungtaskd
   15 root      20   0       0      0      0 S  0.0  0.0   0:00.00 oom_reaper
   16 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 writeback
   17 root      20   0       0      0      0 S  0.0  0.0   0:00.00 kcompactd0
   18 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 crypto
   19 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 kblockd
   20 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 watchdogd
   21 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 rpciod
   22 root       0 -20       0      0      0 I  0.0  0.0   0:00.00 xprtiod