Webcam server with TL-MR 3020?

Hmm. Previously, I build two nice webcam-servers out of Fonera 2.0g boxes (German posts: 1 & 2). cpuinfo of the Foneras is as follows:

root@cam-serv3:~# cat /proc/cpuinfo
system type             : Atheros AR2315
processor               : 0
cpu model               : MIPS 4KEc V6.4
BogoMIPS                : 183.50
wait instruction        : yes
microsecond timers      : yes
tlb_entries             : 16
extra interrupt vector  : yes
hardware watchpoint     : no
ASEs implemented        :
shadow register sets    : 1
core                    : 0
VCED exceptions         : not available
VCEI exceptions         : not available

There I run two jobs, for /dev/video0 and /dev/video1, of mjpg_streamer -i input_uvc.so -f 10 -r 960x720 ..., which results in this top output:

Mem: 19836K used, 10080K free, 0K shrd, 1140K buff, 6096K cached
CPU:  19% usr  11% sys   0% nice   1% idle   0% io  31% irq  34% softirq
Load average: 2.57 2.51 2.45
  PID  PPID USER     STAT   VSZ %MEM %CPU COMMAND
 1518  1064 root     R     8732  29%  33% mjpg_streamer -i input_uvc.so -d /dev
 1517  1060 root     R     8572  29%  26% mjpg_streamer -i input_uvc.so -f 10 -
 1065  1064 root     R     8732  29%  20% mjpg_streamer -i input_uvc.so -d /dev
 1061  1060 root     S     8572  29%   7% mjpg_streamer -i input_uvc.so -f 10 -
 1577  1520 root     R     1960   7%   6% top -d 2
 1519   933 root     S     1996   7%   1% /usr/sbin/dropbear -p 22
 1064  1058 root     S     8732  29%   0% mjpg_streamer -i input_uvc.so -d /dev
 1058     1 root     S     8732  29%   0% mjpg_streamer -i input_uvc.so -d /dev
 1067  1064 root     S     8732  29%   0% mjpg_streamer -i input_uvc.so -d /dev
 1060  1056 root     S     8572  29%   0% mjpg_streamer -i input_uvc.so -f 10 -
 1056     1 root     S     8572  29%   0% mjpg_streamer -i input_uvc.so -f 10 -
 1066  1060 root     S     8572  29%   0% mjpg_streamer -i input_uvc.so -f 10 -
 1055     1 root     S     1976   7%   0% udhcpc -t 0 -i ath0 -b -p /var/run/at
  520     1 root     S     1972   7%   0% udhcpc -t 0 -i eth0.1 -b -p /var/run/
[...]

Recently I joined the MR3020 hype, them being quite similar to the Fonera 2.0g systems, i. e. Atheros-based, supported by OpenWR, rather cheap (<30 EUR) and with USB; only drawback is the ridiculously small on-board Flash:

root@cam-serv5:~# cat /proc/cpuinfo
system type             : Atheros AR9330 rev 1
machine                 : TP-LINK TL-MR3020
processor               : 0
cpu model               : MIPS 24Kc V7.4
BogoMIPS                : 265.42
wait instruction        : yes
microsecond timers      : yes
tlb_entries             : 16
extra interrupt vector  : yes
hardware watchpoint     : yes, count: 4, address/irw mask: [0x0000, 0x0280, 0x05d0, 0x0630]
ASEs implemented        : mips16
shadow register sets    : 1
kscratch registers      : 0
core                    : 0
VCED exceptions         : not available
VCEI exceptions         : not available

But to my big disappointment, running even only one process of mjpg_streamer, /usr/bin/mjpg_streamer --input input_uvc.so --device /dev/video0 --fps 1 --resolution 1280x720 ..., seems to max the system out, and anything above 1 fps, I tested 2, 5, 10, gives quite chopy images, distorted in odd ways. top says:

Mem: 25868K used, 3308K free, 0K shrd, 1412K buff, 5392K cached
CPU:   0% usr   0% sys   0% nic  97% idle   0% io   0% irq   0% sirq
Load average: 0.06 0.11 0.11 1/41 1542
  PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND
 1514     1 root     S    24424  84%   0% /usr/bin/mjpg_streamer --input input_
 1541  1431 root     R     1496   5%   0% top -d 2
 1430  1362 root     S     1216   4%   0% /usr/sbin/dropbear -P /var/run/dropbe
 1431  1430 root     S     1504   5%   0% -ash
  592     1 root     S     1504   5%   0% /sbin/syslogd -C16
 1140     1 root     S     1504   5%   0% /sbin/udhcpc -t 0 -i wlan0 -b -p /var
...

So, it does not seem to be a CPU limitation; the CPU should be even more powerful than the Fonera’s, and the minor increase in resolution, 1280×720 instead of 960×720, should be compensated by far by the two USB cams served by the Fonera. Any opinions or tips?