A long time ago, in a galaxy far, far away… oh sorry, wrong script. I’ll start over. In the dim and distant past, I wrote about my efforts to eke a little bit more performance out of the WordPress installation that this glorious website runs upon. What I’d done was fairly basic: content compression, reduced page weights, database tuning… the usual stuff.

I also described how I’d failed to get WP Super Cache working and wrote that I was investigating PHP accelerators. Yet, despite my endeavours, the website’s performance continued to be, well, pitiful. Some time later I managed to get WP Super Cache working and things improved, but were still disappointing to me.

I come from a mod_perl background and one of mod_perl’s strengths is the speed at which it can run its applications. The PHP app’s that I now find myself working with just can’t compete. I believed that I’d just have to accept that the performance goals I was aiming for weren’t achievable.

However, I was recently forced to reconsider my position when I was contracted to build a website on top of the Zend Framework — because, despite being written entirely in PHP, nursesstore.co.uk turned out to be very fast.

Suddenly, I knew that it was possible to build fast PHP applications. So I turned my attention, once again, to the speed-deficient Urban Mainframe with the fire of the true zealot burning in my eyes.

I’d read about the performance improvements that accelerators like APC can provide and I’d half-heartedly tried a couple of times to get it running on my Media Temple GS server. Yesterday I actually managed to get the thing running and I saw immediate improvements in the speed and responsiveness of the Urban Mainframe.

Whilst I was researching the APC software I came across a reference to something called W3 Total Cache and, as I read about it, I began to get very excited about its features and the apparent benefits it offered. So I installed and configured it and it is now working away in the background — improving the performance of this site with an aggressive caching policy.

W3 Total Cache has the ability to transparently integrate with a CDN to further improve on a website’s performance. In order to benefit from this, I set up a sub-domain on this site to handle its static assets and linked that in with the W3 Total Cache configuration.

To summarise then: I’ve made three big changes to the site’s architecture in my quest for a speed boost.

1. APC bytecode and object cache
2. W3 Total Cache for cache management and integration
3. Sub-domain based CDN for asset delivery

There’s still a lot of work to do in order to take full advantage of the new architecture — I’m only managing a Grade D in YSlow at the moment — but I’ll continue to refine things until I get that Grade A.

Let’s see how we’re performing at the moment:

Concurrency Level:      10
Time taken for tests:   91.877 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      9861992 bytes
HTML transferred:       9406000 bytes
Requests per second:    10.88 [#/sec] (mean)
Time per request:       918.771 [ms] (mean)
Time per request:       91.877 [ms] (mean, across all concurrent requests)
Transfer rate:          104.82 [Kbytes/sec] received
Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:      168  405 443.4    173    3151
Processing:   414  505  95.6    480    1465
Waiting:      226  305  73.7    285    1272
Total:        589  910 457.9    673    3792
Percentage of the requests served within a certain time (ms)
50%    673
66%    723
75%    911
80%   1548
90%   1621
95%   1669
98%   1827
99%   2586
100%  3792 (longest request)


The output from ab (above) is encouraging. It’s still slower than nursesstore.co.uk but it’s certainly a lot quicker than it was before and the “10.88 requests per second” is certainly acceptable.

Is it Digg-proof? I suspect not. But it’s faster and more responsive than it’s ever been and there’s still areas where I’ve got room to improve things.

Still to do then:

• Implement memcached
• Transition ALL static files to the CDN sub-domain
• Achieve the YSlow Grade A
• Reduce page weight