The majority of what I do to speed up my website is on the server level. In 2009 I moved to a VPS, and just last year I switched to a Smart Server. I have access to install APC, to tune MaxClients, and to upgrade my PHP whenever I darn well want to. And I regularly use these tools to fine tune my server so it’s lean, fast, and efficient. 75% of why my domains run this fast under this much stress (I have two fan sites, they get hammered), is that I’ve done all this work, including some of the stuff I did on DDOS prevention.(My CT_LIMIT is set to 75 right now, and that seems to be the perfect balance. The only people hurt are some silly people in Brazil who like to open 100 pictures all at once. I’ve explained why this is bad.)
However, not all of you have access to the server to make all those cool tweaks and changes to speed up your website. If you’re on shared hosting (and there’s nothing wrong with that), you can’t edit httpd.conf, you can’t always edit php.ini, and you sure can’t upgrade PHP on your own. Don’t worry, there are still things that you can do!
The first thing you should do is understand that the more complicated your site is, the slower it’s going to be. So if you want a site with all those bells and whistles, you have a lot more work to do than a simple, plain, site. These are the tradeoffs we must accept in all things.(The exception being, perhaps, cookware. I have some awesome Lodge cast-iron pots and pans, and they’re pretty expensive for their simplicity. Then again, they’re made with such amazing skill and precision, they’re not ‘simple’ to make. So YMMV.) Reduce the complications and things run faster. You have to have a balance between ‘everything’ and usability. If your site is sexy as all get out, but slower than a truculent five year-old on a family walk, then you’re doing it wrong. That doesn’t mean you need to have the world’s most boring site, it just means you have to start learning what it is that makes your site slow. When you look at themes and plugins for a site, remember the more you have, the slower things may become, so use them wisely.
My favorite tools to show why a site is slow are YSlow and PageSpeed. YSlow is a browser add-on you can use with Chrome, Firefox, and every other commonly used browser. Except for IE. Once installed, you simply go to the webpage and run the tool to get a scan of your site. You get ‘graded’ on an A through F scale, with F being the worst, and the grades are computed based on a fairly understandable methodology.(See FAQ: Grading) Page Speed is Google’s version, and I prefer it, but only because I don’t have to install anything to do it, and it gives really good explanations of what’s wrong. There’s also Web Page Test, which is great to find out if your site flails on different browsers, as well as giving you accurate speed breakdowns.
Here are three of my sites, all installed on this server, scanned by YSlow:
And here are the same three as SiteSpeed:
I’m not going to go through every option, most of them are self explanatory (put the CSS at the top and JS at the bottom). Instead, I’ll explain the weirder ones that you can tweak yourself, and some that you can ignore. If you’re using a tool like W3 Total Cache, you actually can configure most of this directly in the tool instead. For what it’s worth, I did ‘fix’ my scores with both sites and I’m now in the 90s from Page Speed and .. Well not so much with YSlow. The two disagree on how much ‘weight’ to give various errors. Page Speed thinks minification is low priority, and doesn’t judge you about a CDN. It also understands that you can’t gzip what you don’t own. If you use YSlow, make note of what you score poorly in, and fix those as best you can.
Things I Ignore
When I get complaints of too many HTTP requests, that just means I’m calling ‘too many’ JS scripts and stylesheets. YSlow doesn’t say which ones those are, which isn’t actually helpful to the novice. If you click on ‘Read More’ it just explains why this is bad. The idea here is that you should have one CSS file, but realistically, any dynamically generated site is going to have more that one. Especially when you consider I’m calling some from Google, Facebook and Twitter for my sharing buttons. While this does slow your site down, unless you have 20 stylesheets on your own site (again, I’m not counting the ones on other domains), it’s not that big of an issue. If you minimize what you have, and combine as much as you can, you’re going to be okay.
I also totally ignore any scores related to my CDN, or rather the fact that I’m not using one. Yes, a CDN will make your site much faster, but I don’t think this is applicable for everyone, and I generally ignore that value.
Finally I ignore suggestions to use cookie-free domains, but that’s because I’m running WordPress, and it needs cookies.
Things I Fix in .htaccess
You can fix most expires headers errors, but only the ones that relate to your site. When I look at a scan for one of my domains, I see that the items my site loads that don’t have Expires headers are a flash module from PayPal, Google’s +1 javascript, a banner, and two gravatars. Those are all items that, yes, can slow my site down, but they’re outside my ability to fix! And in the case of gravatars, I don’t want them to Expire too soon, since they may change. I’m going to, again, ignore this.
Why wasn’t my server listed? It’s because I added Expires headers to my site. Obviously. The easiest way to do this for your site is to put the following in your .htaccess file(If you’re using WordPress, Drupal, or any web app that has it’s own .htaccess rules, remember to put these above the section for them! It’s important.):
<ifmodule mod_expires.c>
<filesmatch "\.(jpe?g|gif|png|css|js)$">
ExpiresActive on
ExpiresDefault "access plus 1 year"
</filesmatch>
</ifmodule>
What this will do is turn on Expires and set to to today plus one year. Now this isn’t actually the best way to do it, as it leaves out a lot of variables, but for most people, it’s good. Keep in mind, the further you set out this expires, the harder it is to change any files! For example, if I upload a PNG with a 1 year expiration, and then upload a new version, no one will see it (unless they flush their browser cache). Don’t set this further than a year, and only set it for things you know aren’t changing often.(You’ll notice WordPress sourcecode has your JS and CSS files saved with ?ver=x.x at the end. This lets you work around the expires, as when you change your CSS, it changes the version, and thus, pushes the changes down to your users.)
Cache-Control is the half-sibling of Expires, and lets you specify what files should be cached and for how long. The Ask Apache site has some great examples, as this is what I generally use:
# 480 weeks <filesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$"> Header set Cache-Control "max-age=290304000, public" </filesMatch> # 2 DAYS <filesMatch "\.(xml|txt)$"> Header set Cache-Control "max-age=172800, public, must-revalidate" </filesMatch> # 2 HOURS <filesMatch "\.(html|htm)$"> Header set Cache-Control "max-age=7200, must-revalidate" </filesMatch>
The ‘must-revalidate’ tag is what makes sure your webpages changes actually get picked up quickly. Nothing’s worse than editing a typo, and not having it fixed for your readers!
Related to that is ETags, which is a bit weird, but this too is something you can tweak. If you disable ETags, everyone has to trust your cache and that gives you a lot of control. It sounds easy, but there’s a reason we should be using ETags for some situations. My sites are using a pretty complex rule that was set by W3TC for me. It sets my Cache Control and ETag, generating the rules I need. If you just want the basics, though, AskApache’s Speed Tips: Turn Off ETags will get you there. For what it’s worth, a small site doesn’t need to worry about this too much.
If you want to grab my default .htaccess starter, here you go!
Things I Fix via CPanel
You can also speed up your site by enabling gzip. I’d say I left it off on purpose to show you the error, but the fact is I forgot to turn it on when I moved to a new server. If you have cPanel, this is stupid easy. Log in, go to ‘Optomize Website’ and turn it on.
Doing improved a lot of results on my site, though it didn’t want to consider three of my .js files gzipped for some reason, though it did on other domains on the same server when I changed it. I’m not terribly concerned at this point, since I used the HTTP Compression Test (from What’s My IP?) and it says I’m compressed.
Things I Fix with Elbow Grease (or Plugins)
Minification. If you view the source of this site, it’s ugly. Everything’s all crammed up without line breaks, and finding anything is a hassle. That’s because I minified my content. If you don’t have a plugin or add-on for your site that can do that for you, you’ll need to do this manually, via Minify CSS and Minify JS. It’s more of a hassle to do that manually, since it’s hard for you to edit later. After-the-fact compression can slow your site a little, but it’s easier to maintain and still faster than non-minified code. Now I use W3TC, which has a minification tool built in, but there are other WordPress plugins that do the same thing.
The Rest
There are a lot more tips and tricks to getting your site running faster. I mention W3 Total Cache (W3TC) multiple times because it works great. There’s also WP Super Cache, which I prefer for smaller hosts and shared servers. W3TC is very, very, very complicated, so be warned. WP Super Cache isn’t a ‘lesser’ tool, it’s just different, and I advocate using either one if your site is moderate to large.
If your site is small, you really can get by with just minifying. There are a lot of minification plugins out there. Images can be reduced in size by compressing them more via Smush.it (there’s a plugin called WP Smushit for WordPress). Many people have also suggested using a Lazy Load plugin, like jQuery Image Lazy Loading, which loads images on demand. I like it, but it slows my site down, and doesn’t work well at all on ones with a lot of dynamic images. I may be using it wrong.
Anyone can take advantage of a free CDN, Cloudflare has a free plan.(Caveat: I don’t use CDN, nor have I looked at Cloudflare in depth.) They claim to protect you as well as speed things up, and I’ve heard interesting (good) reports on it.
Many people advocate using plugins to tune your database, but I really don’t like using a plugin for that. You can optimize your database with a cron job instead, or even just do it manually now and again, if you think your site is sluggish. For WordPress I limit my revisions and empty my trash more often with two lines in my wp-config.php:
define('WP_POST_REVISIONS', 5);
define('EMPTY_TRASH_DAYS', 5 );
When all else fails and nothing you can do speeds up your site, take a look at your server. If the server itself is really slow, all the time, and I mean you can hardly get your email, ask your host if you can be put on another cluster. A lot of shared hosts are oversold, since not everyone needs all the space and power. It makes sense, but some hosts monitor the status of these servers and move people around if they become bad neighbors, while others wait for you to notice. Opening up a line of communication with your host is always a good thing. Remember, you’re paying these guys! They should be willing to help you out, or you should leave and get a new host.
At a certain point, you’ll notice that the only ‘fixes’ are to throw more money at it, buying a better host, better themes, better tools, and so on. And that’s simply a fact of life. You can’t live forever on ramen and hot dogs.
Lorelle said it right when she said there were 
So when you look at all that, you may wonder if there’s a plugin I can’t live without. The answer is a flat out no, but you’re not asking the right question.
If you’re going to have a website, it’s incumbent on you that you’re mean to yourself. You hear the horror stories of clients who want all sorts of crazy things on their sites, and there’s a reason a lot of us sit and laugh (and cry) when we read the Oatmeal’s 
This most often comes up when someone is suffering content theft. Invariably, someone will see their hard written prose on some scammy person’s site, and want it taken down. This is, sadly, harder to do than we’d like. Basically you have to find the site owner, contact them, ask them to take the stuff down, hope they do it, and when they don’t, go up to their webhost. I’m not going to get into the copyright issue, and just assume you know not to attack someone over links to your site (not illegal), rss feeds pulling excerpts from your site (ditto), or quotes (really?). If you don’t know what is and isn’t copyright/content theft, then you’re not ready for this yet.
It was asked why I don’t recommend using www in your URL for Multisite in 
To explain what that means, www used to be the protocol to say ‘If data comes for www.example.com, it’s web traffic.’ Similarly, mail is the protocol for email, and mail.example.com sends traffic to your mail server. You could email me at mail.halfelf.org. And the point of all that all web browsers today know that http://example.com is a website. In fact, you can just type example.com into any browser, and it’ll know ‘Oh, this is a website.’ How does it know that? Because you’re in a web browser.
A common enough request in the WordPress forums is people wanting to have two sites on a MultiSite network have the same content. Usually I take the time to ask why they’re doing this, and see if there are better ways around it. Like if you want to have a collection of ‘all’ posts, then you want 
Splitting up your visitors means you have to figure out how to push content that is identical. This is not difficult, but it can cause problems. Every time you edit a post, the PHP calls your database and overwrites things. Multiply that by however many places you’re overwriting, and that could slow down posting. But then you think about using something like 
You’ve heard people say that if you’re not paying for something, then you’re the product? That’s never more true than with Tumblr. On this site, my content is generated by me, and the additional UGC (User Generated Content) comes in the form of comments. I can see my ‘value’ based on retweets, +1s and likes, but it’s in communicating with you commenters (and I try to talk to everyone) that I find out what’s engaging in my posts, what’s important, and what I get wrong. Oh yes, I get things wrong.
And now we’re at the crux of why Tumblr is so cumbersome.