How to Resolve CPU Throttling / Performance Issues in BlueHost

If you are using BlueHost and have ever experienced limiting factors (CPU throttling), then hopefully this post will help you solve some of the issues that may be causing high CPU usage.

What is ‘CPU Throttling’?

BlueHost uses a proprietary CPU throttling system which automatically ties your account to a dedicated core on a temporary basis, to keep it from dominating too much CPU. BlueHost states that generally throttling for less than 600 seconds in any given hour will not usually affect your website or your blog’s performance for your visitors. However in some rare and extreme cases a member of their technical team may temporarily suspend accounts until the problem has been resolved.

So the big question is, how do you optimize your website should you ever face throttling issues, and how can you tell?

Before you go off thinking you need to be spending money on a CDN service read the following first…

Here’s my story…

A few days ago my blog received an overwhelming number of visitors in the space of just a few hours, check out the screen capture below. The visitors didn’t appear to come to the site naturally either, according to my Google Analytics report high traffic was coming from one single IP or demographic location, (New York).


At one stage I even thought, was it because I shared a post on StumbleUpon, was I getting a lot traffic from StumbleUpon? but the stats didn’t cross reference well, so I’m still puzzled to how the traffic came pouring in just from one demographic location that day.

Anyhow I logged into my BlueHost account to check the CPU Throttling just out of interest, and saw it was through the roof… it was actually warning me that my account had been throttled for 18,000 seconds in the space of 24 hours. I thought this couldn’t be good, if this continued my account would surely be suspended… the screen grab was taken 24 hours later…

CPU throttling

After a short burst of panic (as usual), I thought; I need to think how to stop this traffic coming to my site, as this had to be the reason why CPU throttling was going through the roof.

So I identified the IP to where the excessive traffic was coming from in latest visitors log in BlueHost, once identified I then blocked this IP from accessing any of the sites on my account in the IP deny manager folder. That little trick seemed to work instantaneously, just like turning off a tap left to run, the traffic went down and back to normal.

CPU throttling2

I unblocked the IP after 24 hours and the traffic remained normal, I continued to monitor the CPU throttling also after 24 hours, although the usage had reduced greatly, it was still relatively high.

So I decided to take further action…

I logged into my blog’s admin and performed the following maintenance routine –

1. First I deactivated 2 plugins  – which I recently installed, activated and started to use a few days before this CPU issue began to happen. Those plugins were –

Plugin 1. Broken Link Checker, I deactivated and removed this because for some reason it wasn’t working properly as it use to, I don’t think it was causing any issues with CPU usage.

Plugin 2. AWPCP Classifieds plugin. Six hours after deactivating and removing this plugin I saw the CPU throttling reduce dramatically. After finding and reading this post on the web, I am now 100% positive that this plugin was the culprit, (sending too many queries, causing high CPU usage). To think I reviewed this plugin recently too… I will be updating the review of this plugin shortly.

2. Installed the CleanOptions plugin – I then installed the CleanOptions plugin to find and remove any orphaned files and clean up the database. Although this plugin has not been updated for over two years, it’s still a useful plugin.

3. WP Super Cache – After that, I cleared the cache, I use WP Super Cache, and continued to monitor the CPU usage, which I’m pleased to report is now stabilizing, although there are still the odd hour with high usage. If there are any other plugins I need to address and remove I will do so.

I also enabled CloudFlare CDN, a free service provided to BlueHost hosting account members.

Lessons learned…

Be careful which plugins to use before installing them into your blog I guess. But it may not just be plugins that cause CPU throttling issues, it can be down to the theme also. For me, if the plugin issue and the traffic spike are somewhat related, I really don’t know how. I also read on this forum how certain plugins don’t respect CPU usage, I was alarmed to see the SEO plugin by Yoast one of them.

Over to you folks, have you ever experienced CPU throttling issues with BlueHost? Share your comments below as always…

About Fabrizio Van Marciano

Fabrizio Van Marciano is the founder and editor of Magnet4Marketing Blogging and Online Business Tips. You can learn more about him here and follow him on -
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  1. Fabrizio, Nice tutorial on how to monitor and keep CPU usage in check. I’ve done this quite a bit when my blogs were on Hostgator. However, that does not help if you are serious about your blogging, you should move like I did. I have my blogs hosted on Inmotion hosting, VPS.

    They are worth it because they offer more than what any other VPS service provider offers. I strongly recommend them. Shared hosting is just not worth the money your investing especially if you are running a blog with over 25000 visitors monthly.

    • Hey Eddie, thanks for stopping by mate, yeah I’m still seeing the odd hour of weird high CPU usage, but will keep an eye on it. I’m in two minds whether to stay with BlueHost when it expires in a few months time or to move it to a VPS. That might be the case.

  2. Thanks for this Fabrizio! I had a very similar issue recently (full story in commentluv link)! I decided to upgrade to VPS since I have a bunch of sites on my shared hosting. Hope all is well now?

    • Hi Jane, glad you liked the post :) All is stable for the time being but will be keeping an eye on it. I’m also thinking seriously about upgrading to VPS, I’m heading off to check out your post thanks.

  3. Samantha Wright says:

    So has the throttling improved? What’s the cloudflare cdn like? you should do a review of it :) Maybe Eddie’s right we should move the blog over to a VPS.

  4. So what have you thought about the Hosting service provider Fab?? Are you going to change the service or want to remain on that.
    But i guess its not the fault for which it has to be blamed.I hope you will soon be able to tackle with this problem completely Fab.Is this problem is on this blog or your other blogs??

    • Hey mate, I’m still a great fan of BlueHost though I have to be completely honest, their technical help wasn’t that great, they simply just asked me to block the IP where the high traffic was coming from, instead of looking at the possible plugins that could be causing the problem. I’m not saying BlueHost’s technical team aren’t that good, but I really thought they could help a little more.

      I believe it was just the Magnet4Marketing blog that was causing the issues, high traffic and dodgy plugins added to the mix wasn’t good.

      Right now we’re in the process of looking elsewhere I think, Samantha and I will probably talk about moving the blog over to HostGator VPS this weekend :) Or maybe we’ll wait another week or so. I’m a bit unsure lol. What do you think?

      • I think you have to ask Jane for that she has shifted her blog from HostGator.She will be of great help on this.
        But if you ask me i too have shifted my site from Hostgator a couple of months ago.

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