Posts Tagged ‘performance’

Leeds Restaurant Guide is incredibly detailed covering so many restaurants with high quality content and imagery. So it seemed only fitting that I should pay as much attention to the presentation as I do the content.

I’ve been using Google’s PageSpeed Insights tool to debug it. Ironically, PageSpeed Insights spends a lot of time complaining about the Google AdSense code that they provide to me. It does however provide some useful tips too.

Compression

Gzip compression costs almost nothing and can drastically reduce the file size you are sending to the client. The server compresses it and the client uncompresses it all of which is done transparently to the user.

It is pretty easy to configure using Apache’s mod_deflate module, and I’ve blogged about how to get it working on cPanel on Hardware Tutorials.

Expiry headers

If you have Apache’s mod_expires, and you almost certainly do, you can set default expiry headers for content using your .htaccess file.

<IfModule mod_expires.c>
    ExpiresActive On
    ExpiresByType text/css "access plus 60 minutes"
    ExpiresByType image/jpeg "access plus 1 day"
    ExpiresByType image/jpg "access plus 1 month"
    ExpiresByType image/png "access plus 3 months"
</IfModule>

This will tell the client it can safely cache the content for a while. Put whatever values in that you think are sensible.

Minify your CSS

Recently I wrote about how to use Gulp to set up a task to compile your SASS/LESS stylesheets. This included instructions on how to minify your CSS. Even if you are just using plain old CSS, you could still create a task to create a minified version.

Minification takes out all the spaces, comments and other unrequired characters so that you have less data that needs to be transferred to the client.

Using gzip compression allows you to deliver website content faster as it can be gzipped on the server and uncompressed on the client, reducing the file size you need to transfer.

Unfortunately mod_deflate, the Apache module required to do this, is not enabled on all cPanel installs. However, if it is, or you have access to the server, you can easily enable it.

Enabling mod_deflate

If you do not have mod_deflate, you need to use EasyApache to add it. Log in to Web Host Manager and go to EasyApache (only server admins will be able to do this). Select build from the previous configuration and customise it until you get to the exhaustive options list.

Check the box next to mod_deflate and then re-build Apache.

Enabling compression

Once you have mod_deflate enabled, cPanel will have a new option. Under “software and services” in the x3 skin you fill find an option called “optimise website”. Click through to that page.

Compress content will probably be set to “disabled”.

Select “Compress the specified MIME types” instead. You could enable it for all content but I would not recommend this as some content you will not want to compress and much of it (images for example) is pretty pointless. The third option allows you to customise.

By default it should have the following options:

text/html text/plain text/xml

I recommend adding some more:

text/html text/plain text/xml text/css text/javascript

Hit “update settings” and you are done!

If you need super quick access to a file, for example a log file which isn’t going to be too big but it being used by a script which is time critical, then rather than writing it to disk, you can mount part of your file system in memory and write to it there.

This has the disadvantage that when you restart your system, you will lose the data. But for test scripts, logs or other temporary files that you don’t mind getting lost, it can really speed up performance.

Luckily, most systems come with a an area mounted in memory already – so you don’t even need to configure it!

cd /dev/shm

If said directory exists, you’ll have a memory mounted directory already and can start using it immediately.

If you have a complex SQL query, you might find that performance isn’t exactly ideal. Worse still, you don’t actually know which part of the query it is that is actually taking so long.

Luckily, MySQL comes to the rescue with the ability to explain.

All you have to do is start your query with the keyword EXPLAIN and MySQL will, rather than returning you a recordset of results, will instead provide a break down of everything it has done, including how it made the table joins and what order it did everything in.

EXPLAIN SELECT a INNER JOIN b ON a.col1 = b.col2 WHERE a.col1 > 1 AND b.col2 > 2;

If your insert statements are not time critical, you can use insert delayed in your SQL to speed things up. The syntax is as follows.

INSERT DELAYED table (col1, col2) VALUES ('a', 'b');

Insert delayed can be used with MyISAM and Memory, but cannot be used with InnoDB.

The advantage of using insert delayed is that the MySQL server returns a success message straight away so the script can keep going, without it actually having to do the insert. This allows the MySQL server to carry it out when it isn’t busy, and do several at the same time.

It’s appropriate for tables such as logs tables where it doesn’t matter too much if they don’t go in straight away.