CCR 1036 - bonding pps limit?

Has anyone noticed any limitation on the bonding interface?

I have 4 gig ports bonded on a CCR1036 connected to another CCR1036.

I use mode ‘balance rr’.

If iI do bandwidth test (UDP, 1500bytes) I can see all ports being used, but the pps will never go above 140000 limiting the total bandwidth to ~1.6Gbit instead of reaching a full 4gbit.
Screenshot_3.png
By removing or adding more interfaces to the bonding interface doesn’t change the limit of 140kpps.
With a single gbit port it can reach 80-90kpps. So in theory -at least- it should be able to reach ~360kkps with 4gbit interfaces bonded.

Is this a pps limitation of the bonding interface or the bandwidth test tool?
At the moment I don’t have physical access to those CCRs and cannot put some forwarded traffic to check if this limitation is on the btest tool.

Has anyone else encountered this behavior?

Doing the same bandwidth test without bonding, using SFP+ 10gbit links with 2 CCR1036 and a Cisco 3750E in the middle and I still get a maximum of 140kpps and 1.6Gbit.

Is this a limitation of the bandwidth test tool?

CPU load is 0% during the test with no packet loss or any other visible issue with the network.

Can anyone confirm that Bandwidth test tool cannot go over 140kpps / 1.6Gbit ?