Last week, Bluehost sent this notification:
SERVER PERFORMANCE UPGRADE
Dear DOUGLAS,
We’re pleased to inform you that the server hosting your dograt.com website will be undergoing a major software upgrade, from CentOS 5 to CentOS 6, within the next 48 hours.
This upgrade includes newer software packages (including Python, Perl and gcc), as well as all the security and performance benefits that come along with CentOS 6. In addition to this, the server will be redeployed with a different file system type simultaneously, further increasing performance.
Although a bulk of the upgrades to your server are being done with it online and functional, in order to safely finalize these changes our Administrators will need to temporarily take your server offline in the early morning hours. Barring any extenuating circumstances this outage should only last about 2 hours.
Please note that while we do not anticipate your software having problems post-update, it may be required to re-compile any module(s) you are using to take advantage of the newer included libraries. We suggest reviewing your site afterward to verify that it is functioning as it should.
The case can be made that the upgrade actually reduced performance, because after the update was run I saw that Gzip compression wasn’t working. In the cPanel manager for my Bluehost Pro account the Optimize Website option is gone, and that means something called “mod_deflate” in the Apache Web server is no longer supported. So I wrote to Bluehost and here is their reply:
I’m sorry to inform you but we did away with that icon as it caused problems with other things in the hosting account, this was done fairly recently and wont be coming back in the near future or ever that I am aware of.
First they were pleased to inform me, then they were sorry to inform me. From this I am inferring the real issue is that CPU power is more expensive than Internet bandwidth. The loss of Gzip means that every character of text in this post and the page it’s on is being sent, rather than going across the Internet in a compressed format that uses about one quarter the amount of data, before being unpacked by a browser. If I want Gzip compression, I’ll have to force it in PHP, then see if Bluehost’s dreaded CPU throttling returns for the first time since upgrading to their Pro plan.
I received this follow-up message from Bluehost: “Yes we understand the loss of configurable gzip compression does have implication. It was a decision that was weighed upon and ultimately decided on to allow for the best possible server performance. gzip compression is still on but only applies to specific file types.”
From your tech’s note, they only “did away with that icon” so presumably the functionality is still there… 😉