How to decrease the system impact when using kopia

when I use kopia in AWS, the host is with 8 vcpu and 64G, when we use kopia to backup the data, the backup speed is about 1.3G/s, the cpu usage is high, and reach about 97%, so the storage performance is very bad, is there any way to decrease the performance impact? is there any way to limit the backup speed?
since the host is the NFS stroage server, we just use backup in the NFS server, if we did the kopia backup in the NFS client, will the impact to storage server lowwer?
we use the default compression