DEBUG mode enabled, logged as Guest:
Index
* Page Generation 0.01844 seconds
* Memory Usage 553KB
* Queries Executed 4

Forumdisplay
* Page Generation 0.03062 seconds
* Memory Usage 635KB
* Queries Executed 9

Showthread
* Page Generation 0.03081 seconds
* Memory Usage 778KB
* Queries Executed 6

DEBUG mode enabled, logged as Admin:
Index
* Page Generation 0.02090 seconds
* Memory Usage 602KB
* Queries Executed 5

Forumdisplay
* Page Generation 0.03693 seconds
* Memory Usage 714KB
* Queries Executed 10

Showthread
* Page Generation 0.05298 seconds
* Memory Usage 921KB
* Queries Executed 7

I might work on the forumdisplay to lower it even more... but I really don't like to edit the vBulletin code. The above results were obtained while inserting code into hooks.
I think the best part is the memory usage. I lowered it's value from 3500KB to 600-900KB.

I use lighttpd as server software. All applications are set on bleeding edge.
Yes, I hate Apache... it eats memory like an elephant. :)

EDIT: I use both XCache and memcached, on my server.
Since we are here, I wonder if it's better to simply remove the queries or cache them with memcached. Somehow, I think 4 queries on the frontpage is better then 9, even with mighty memcached. Another issue is how to check if memcached is actually caching the queries. If I use -vv, it will give me all kind of huge numbers into the log files. However, memcached lacks on documentation so it's actually hard to know how and when the queries are processed/cached.

Let me know what you think about this matter. Thanks for your advice.

Actually, they count very much. Even if memcached caches your datastore, it will still use bandwidth. Yes you save the processor, but your month bandwidth will increase. On the other hand, if you use XCache... it will chew the disk I/O. The real question is: What is more beneficial, performance wise?

Thanks for the input. :)

That is very impressive TECK

In my opinion, bandwidth will always be cheaper than CPU time or disk. I don't see how moving a query from hitting a MySQL database to memcache increases my bandwidth any, unless you're referring to the traffic between the memcache or database server and your webservers, but I'd hope that any site that is doing enough traffic to justify a memcache setup would most likely have an unmetered private network between their servers.

In my opinion, bandwidth will always be cheaper than CPU time or disk.
Very good point, mute. :)

I'd hope that any site that is doing enough traffic to justify a memcache setup would most likely have an unmetered private network between their servers.
Another excellent reflection.

So what do we do. Do we put emphasis on the memcached or XCache? In other words, more queries and less PHP files to be cached?
Personally, I never liked executing queries. Instead, I cache the query data with XCache... avoiding possible table locks. I have this theory: the less queries you run the easier it is for the MySQL server.

Recently, I had an interesting talk with one of the vBulletin developers and he told me that they are not 100% sure what is the best solution: cache more queries or files.
For example, in vBulletin 4, you will be able to cache the templates as files, on the vBulletin datastore, or directly with memcached.
That is quite ingenious, since you have the liberty to use whatever method suits best your forum.

Please guys, comment more on this issue. Your opinion is important to me.

Floren