I wouldn't say it is an error. I get this response from an Intel PC:
64 bytes from 8.8.8.8: icmp_seq=1 ttl=124 time=7.22 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=124 time=6.96 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=124 time=6.94 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=124 time=7.11 ms
I assume you are using an ethernet connection. The RPi3 does not have a great ethernet setup, it is connected internally to a USB port. Wifi connections will show an even worse performance.
You are also using a pretty old LibreELEC version: 8.2.5 is currently the latest stable build, and we are testing 8.90.006 with Kodi 18 at the moment.