Seems there is an unclassified process eating cpu.
No problem in RB411ah but on older mipsle's:
[admin@a8] > system resource print
uptime: 1h38m21s
version: "5.0rc1"
free-memory: 17100KiB
total-memory: 29612KiB
cpu: "MIPS 4Kc V0.10"
cpu-count: 1
cpu-frequency: 266MHz
cpu-load: 8%
free-hdd-space: 90112KiB
total-hdd-space: 126976KiB
write-sect-since-reboot: 75
write-sect-total: 365124
bad-blocks: 0.3%
architecture-name: "mipsle"
board-name: "RB532"
platform: "MikroTik"
[admin@a8] > tool profile duration=10s
NAME USAGE
wireless 2.5%
console 0.5%
winbox 1.5%
logging 1%
management 2%
profiling 8.5%
unclassified 84%
[[admin@c999] > system resource print
uptime: 10m9s
version: "5.0rc1"
free-memory: 4108KiB
total-memory: 13368KiB
cpu: "MIPS 4Kc V0.11"
cpu-count: 1
cpu-frequency: 175MHz
cpu-load: 27%
free-hdd-space: 35212KiB
total-hdd-space: 61440KiB
write-sect-since-reboot: 214
write-sect-total: 620070
bad-blocks: 0%
architecture-name: "mipsle"
board-name: "RB133C3"
platform: "MikroTik"
[admin@c999] > tool profile duration=10s
NAME USAGE
console 0.5%
flash 0%
winbox 1%
logging 2%
management 4%
profiling 14%
unclassified 78.5%