Ruuvitag-listener problems with 2.5.9 firmware?

3B+ should be able to handle 20 tags. Is this Pi running other applications?
I think some tuning should fix this.

What are you requirements for update interval?
What interval are tags transmitting ? 1sec? 5sec?
Have you tried adjusting

ruuvi-collector.properties
measurementUpdateLimit=30000

to reduce the number of insertions into the database.

Are you seeing log messages indicating out of memory ?
How often does the problem occur?
Does it “self-correct”?

You might also look into these settings in /etc/influxdb

wal-fsync-delay = “5s”
cache-max-memory-size = “300m”
query-timeout = “90s”
log-queries-after = “10s”
log-enabled = false
suppress-write-log = true
level = “warn”

retention policy can also have a big impact. See: