About 10x less insert performance with Galera cluster

I am running an application which inserts a lot of rows and we were experiencing some low performance. So i started benchmarking the Galera Cluster with sysbench and oltp_insert.lua. The performance of the cluster is really bad.
With the same test:
As a standalone DB i can perform about18000 tps
With Galera the performance is: 1000 tps
I try to decrease cluster size to 1, but the result is still bad.