When we think of it, LG comes across as a manufacturers that sort of allows users to root their phone but it does not encourage the activity. For quite some time, the manufacturer has been enlightening the modders and Android power users about the after effects of rooting on the device. LG phones have had easy bootloader unlocking, which made them pretty popular on the developer forums. However, LG seems has been planting a root checking tool on its devices for quite some time. And this tool has been reportedly responsible for downgrading rooted phone's performance by triggering multiple functions together.
Recently, one of the XDA members, dimm0k found out an unusual performance lag on rooted LG phones. After looking into the matter further, the problem was being caused by Root Checker Tool.
Dimm0k was trying to investigate the cause of slow performance on his rooted T-Mobile LG V20 when he noticed multiple ‘sh’ processes that kept triggering on his device. A process called “rctd” that triggers on boot, this process checks for root access and logs the entries. Root Checker Tool (RCT) "rctd" is included on the device by LG and it apparently brings down the performance of rooted devices. According to the LG V20 users on forums, RCT degrades UI performance on the device.
XDA Developers note that they have found similar lags on rooted T-Mobile LG G6 and the European LG G5 (unlocked) on both Marshmallow and Nougat. Sadly, the RCT cannot be disabled by the users and is it is planted deep inside the phone’s boot image that makes it relatively difficult to be fixed by an average Android power user.
Disabling RTC on LG V20 if you're an experienced modder
You can head to this thread to know about disabling the RTC on LG V20. But if you are an amateur then it would be best to not get into such complex processes.
We wonder what's the purpose behind planting RCT to bring down the performance of a rooted device. For now, all we know is that rooting LG devices could bring down the UI performance. So, just be aware.