CPU usage of named daemon on CentOS 6

I'm having an issue with the name server daemon using up more CPU than I can understand. I got to this issue while trying to figure out why the VPS I'm running feels slow.

First off, the problem of named having a high-CPU usage is not new: this question provided me with steps meant to fix the issue. The problem I have is that although I've followed the steps in the detailed answer by @efesaid with success, I still see a quite active and CPU-hungry process.

The server is a VPS running an up-to-date CentOS 6.8 with basic server services and strictly nothing fancy (web server with PHP5.5 support, FTP, e-mail server, and LDAP). yum list installed bind reveals that the version of the installed package is 9.8.2-0.47.rc1.el6.

I've just checked the contents of all zone files and, as far as I can tell, the contents is correct. There are only 4 zones and an average of 6 records per zone.

Here is a screenshot of top (although the display is not sorted by time, I can confirm that named is by far the greediest process – the values in the screenshot represent a rough average of 11.7% over the course of two days):

I've already started to prepare a migration to CentOS 7, and I've installed a VM on my computer for testing. But since this option would require much work, with making backups, reinstalling all software, migrating the data and duplicating/adapting the configuration, let alone testing, I'm left with considering other options.

Although just about every post or message I could find online points to adding managed-keys-directory "/var/named/dynamic"; in the configuration file and stops there, I feel like there's something inherently wrong with a non-serving daemon that never goes idle. I've SSH'ed into my VPS 9 hours ago and it's the only process that has been constantly running.

Is there anything more I can do to figure out what's going on? To be clear, I know there's a problem with the named process and I'm trying to diagnose it.

Also, given that the issue is supposed to have been dealt with in version 9.9.3 and CentOS 6 is using 9.8.2, is using a non official repository that provides an updated version of bind?

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