I purshate 2 RB433AH and detect very low speed on all ether interfaces. Why?
On my old Mikrotik PC router i have 90-100Mbps.

Example with default routeros settings (i only assign IP addresses to interfaces):
[admin@MikroTik] > /tool bandwidth-test 10.20.3.111
status: running
duration: 19s
rx-current: 508.8kbps
rx-10-second-average: 499.2kbps
rx-total-average: 527.3kbps
lost-packets: 0
random-data: no
direction: receive
rx-size: 1500

upd:
between two RB433AH`s bandwith-test showing 80-100Mbps and pins-speed showing similar results, but in simple routing mode or bandwith test PC<->RB i see only 500-600kbps

First of all are you referring to interface as ethernet only or are you referring to all interface like wireless ones.

Secondly, a configuration example is helpful for readers to see in order to help you further.

Finally, When you test bandwidth you should never read acrossed the devices in question. Only through them for true accurate results. Meaning the Bandwidth test server and client software is great, but they have some inherent memory and CPU usage of their own. To get a good representation of speed you should set up like this.

Bandwidth Test Client <->Router One <-> Router Two <-> Bandwidth Test Server

You right now are sounding like your testing this way: Router One with Bandwidth Test Cleint <-> Router Two with Bandwidth Test Server.

1. ethernet only
2.
[admin@MikroTik] > /interface print detail
Flags: D - dynamic, X - disabled, R - running, S - slave
0 R name="ether1" mtu=1500 type="ether"

1 R name="ether2" mtu=1500 type="ether"

2 X name="ether3" mtu=1500 type="ether"

3 X name="wlan1" mtu=1500 type="wlan"

4 R name="bn" mtu=1460 type="pptp-out"


[admin@MikroTik] > /ip firewall filter print
Flags: X - disabled, I - invalid, D - dynamic
0 X chain=forward action=log connection-state=invalid
log-prefix="invalid_packet_"

1 chain=forward action=accept src-address=192.168.12.0/24

2 chain=forward action=accept dst-address=192.168.12.0/24

[admin@MikroTik] > /ip firewall nat print
Flags: X - disabled, I - invalid, D - dynamic
0 chain=srcnat action=masquerade src-address=192.168.12.0/24

[admin@MikroTik] > /ip route print detail
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme,
B - blackhole, U - unreachable, P - prohibit
0 ADS dst-address=0.0.0.0/0 gateway=212.98.160.243 interface=bn gateway-state=reachable distance=1 scope=30
target-scope=10

1 A S dst-address=10.20.1.0/24 gateway=10.20.3.2 interface=ether1 gateway-state=reachable distance=1 scope=30
target-scope=10

2 ADC dst-address=10.20.3.0/24 pref-src=10.20.3.1 interface=ether1 distance=0 scope=10

3 A S dst-address=172.31.3.0/24 gateway=192.168.1.1 interface=ether2 gateway-state=reachable distance=1 scope=30
target-scope=10

4 ADC dst-address=192.168.1.0/24 pref-src=192.168.1.2 interface=ether2 distance=0 scope=10

5 ADC dst-address=192.168.12.100/32 pref-src=192.168.12.1 interface=<pptp-dolphinik> distance=0 scope=10

6 ADC dst-address=212.98.160.243/32 pref-src=80.249.94.53 interface=bn distance=0 scope=10

It is very simple config...

When i testing PC<->RB CPU utilization on RB 90-100%. This behavior similar to promiscous mode...

you don't have any Queues, do you?

No.
All Queues are empty. I din`t touch anything.

do a system reset, upgrade to v3.16, then also upgrade the Bootloader to v2.18 (just type "/system routerboard upgrade). and then apply only the basic config needed:

- enable interfaces
- add IP addresses
- add routes (depending on setup also a masquerade rule)

then do test

After upgrading routers i didn`t get another results. Average speed on ether interfaces ~500 Kbps (PC-RB433AH-Server).
[admin@MikroTik] > /system routerboard print
routerboard: yes
model: "433AH"
serial-number: "1A7801F4EFFA"
current-firmware: "2.18"
upgrade-firmware: "2.18"

[admin@MikroTik] > /system routerboard settings print
baud-rate: 115200
boot-delay: 2s
boot-device: nand-if-fail-then-ethernet
enter-setup-on: any-key
cpu-frequency: 680MHz
boot-protocol: bootp
enable-jumper-reset: yes

On RB433AH with factory settings i`m geting identical results. Testing results in attachment. Can anybody help me?

Sorry. All problems from my desktop NIC
Problem solved. Much thanks for help!!!!