Increase in memory caused decrease in metrics received

I had a lag in metrics being displayed in my dashboards. This lag increased from 3 mins to 14 mins over the weekend.

The memory on my box was at 95% so I increased the memory from 8GB to 16GB.

Machine spec
OS Version Ubuntu 16.04 LTS
Release 16.04 (xenial)
Kernel Version 4.4.0-103-generic
Docker Version 17.09.0-ce
CPU 4 cores
Memory 16 GB
Memory reservation is unlimited

Storage
Driver -> overlay2
Backing Filesystem -> extfs
Supports d_type -> true
Native Overlay Diff -> true
Memory swap limit -> 2.00GB

The lag is now gone but I have noticed a serious decrease in metrics received.
(carbon.agents.*.metricsReceived)

.

The outage around 10:30 is for machine reboot after memory was increased.

Can someone explain why this is the case?