Server lag

[dubstep]

Hi, anyone know why my server gets lag everytime I change the system time? 

This is the scenarios:

1st scenario: Server is running and under maintenance. I changed the system time to UTC+8 with this command: 

date -s "9 OCT 2018 11:14:00"

After that, my server is now hanging even it has 5Gb Ram, 2 CPUs, 300 HDD Drive (not full).

2nd scenario: I rebooted the VPS of my server to refresh all the processes. The very first command I used after I login thru SSH is the command to set the date then after that, the commands to make the server up. But still, the server still too lag.

3rd scenario: I rebooted the VPS of the server again without doing anything in TIME and yes, the lags vanished. This already happened for 2 maintenance already.

Note: There is no error message(s) in console

Anyone have a suggestion?

Thanks!

Edited October 8, 2018 by dubstep