Lately I’ve been experimenting with increasing performance on my blog, and not just one-click fixes but also looking at code in addition to other things like CDN, cache, etc.
I talked to my host about installing memcache so I can enable it in W3 Total Cache and he seems to think it will actually hinder my site as it will instantaneously max out my RAM usage (which is 1GB).
Do you think he is accurate, and should I try it anyway? My blog and forum (MyBB) get a combined 200,000 pageviews a month.
In fact, having 200.000 pageviews a month, I would go a way from a ‘shared’ host, and buy a VPS or dedicated server or something, Memcache(d) is a good tool indeed, but there is lots of other way you can get better performance.
Memcached is good if you know how to use it correctly, (The w3 total cache memcached thing, doesn’t do the job).
As a performance engineer, I think a lot about speed, but also about server load and stuff. Im working much with wordpress sites, and the way I increase the performance to the maximum on my servers, is to generate HTML pages of my wordpress sites, this will result in 0 or minimal access to the PHP handler itself, which increase performance a lot.
What you then again can do, is to add another caching proxy in front of the web server, etc Varnish, which caches results, which means you’ll never touch the web-server either.
What it will do, is when the client request your page, it will serve the already processed page directly via the memory, which is pretty fast. You then have a TTL on your files, and can be as low as 50 seconds which is default. 50 seconds doesn’t sounds a lot. But if you have 200k pageviews, that means you will have 4.5 pageviews each minute if you had same amount of pageviews each minute. So peak hours doesn’t count.
When you do 1 page view, there will be a lot of processing going on:
Making the first request to the web-server, starting the php process, process data, grap stuff from the DB, process the data, process the PHP site, etc. If we can do this for a few requests it will speed up the performance.
Often you should be able to generate HTML files of your forum too, which then would be renewed each 1-2 minutes, if there is a request to the file. it will require 1 request being processed instead of 4-9 requests (if not more).
You can limit the amount of memory that memcached uses. If the memory is maxed out the oldest entries are pruned. In CentOS/Debian there is
/etc/default/memcachedand you can set the maximum memory with the-mflag.In my experience 64MB or even 32MB of memcached memory are enough for WordPress and make a huge difference. Be sure to not cache whole pages (that fills the cache pretty fast) instead use memcache for the WordPress Object Cache.
For generall Performance: Make sure to have a recent PHP Version (5.3+) and have APC installed. For Database Queries I would skip W3TC and go directly for the MySQL Query Cache.