low vxlan throughput with tso enabled

Hi!

I have a vxlan tunnel established between two network interfaces, which
both have a MTU of 1500. The vxlan interfaces have the same MTU.
With TSO enabled, I observe low throughput with TCP connections (<100 kB/s).
Disabling TSO works around this issue and throughput is as expected.
Can someone please explain how TSO is influencing the tunnel to cause
such a difference?

Kind regards,
Reiner