After increasing packet rate, critical error occurred

I have increased packet rate to reduce loading time and to make our response speed faster.
(The speed I found faster is much faster than what you can see on Starter.FPS)
At first, it seems to have no problem at all.

But after few test games I could notice that there is a critical error after increasing packet rate!

The screen gets frozen randomly and to get out of the game, I needed to shut down the game with the window command or sometime had to restart the whole computer. It doesn't happen frequently and there isn't any rule on this but it happens randomly.

To explain what I did exactly,
I have changed the below:

checkPacketSend(false) -> checkPacketSend(true)

After changing that my loading and response speed got noticeably faster.
But somehow client sides gets frozen screen and cannot normally exit game after that happened.

I believe this is happening after increasing packet rate. My dedicate server side is running infinite loop with the full usage of CPU.

My question is "by doing what I have done, can this kind of error happen?"
If so, is there any way to solve this?
And also if you have other thoughts please let me know!