Deprecated - Performance and scalability

Greetings everyone.

I have been running my site on a dedicated server, but since I have a relatively low traffic site [approx. 3,000 unique hits a day], I am deciding for financial reasons to move to a cheaper Xen 256MB VPS solution. [I have been following with great interest Khalid's postings about Xen VPS solutions.]

However, I have noticed a significant degradation in page execution time, during this migration to the Xen VPS.

For example, on the dedicated server the page "The Latest" executes as follows:

Executed 462 queries in 584.05 milliseconds. Queries taking longer than 5 ms and queries executed more than once, are highlighted.Page execution time was 1142.96 ms.

Whereas for the Xen 256MB VPS the page execution time is more than double:

Executed 460 queries in 765.61 milliseconds. Queries taking longer than 5 ms and queries executed more than once, are highlighted.Page execution time was 2901.89 ms.

Is this kind of page execution time normal for drupal on a 256 MB Xen machine? That is to say, is this as good as it gets? :-(

I have tried to follow the suggestions from the excellent www.2bits.com site.

1) I have installed lighttpd with fastcgi rather than apache to decrease the memory footprint.

Not sure if this is the right topic to post this under, but here it goes. I've setup a site where I have a bunch of templates which I've designed and themed for the website part. Problem is when I login to the admin console through a second browser instance and then go back to the first browser, the first browser changes to the admin console. I checked the session table and it is obviously sharing the one session even though I am using two different browsers. Based on what I can see of the session table it records the uniqueness of the session by the host.

OpenCraft hosted a 3.5 hour seminar that I presented on Drupal performance tuning and optimization. You can find the slides from the presentation there, which can be useful to some of you.

I create a 5.2 and 6.x patch for measuring how much memory a module takes, and also how much the whole Drupal page load takes.

The results are published here: Measuring memory consumption by Drupal bootstrap and modules.

Short version: in Drupal 6, modules are better off than in 5.2, but the bootstrap is a tad larger.

I have noticed that when running Drupal behind a cluster, it only returns the IP address of the outward facing servers, and not the actual IP address of the visitor.

You can imagine the chaos this creates when a module such as SPAM blocks that IP address..

The solution is relatively simple:

Change any references to REMOTE_ADDR in the code (in core it's in session.inc, session.inc, and bootstrap.inc), over to HTTP_X_CLUSTER_CLIENT_IP...

Hello.

I'm having trouble displaying the page I want to see after I filled up a form within the block module I created in Drupal 5.1. This module is supposed to retrieve a list of links externally. What's happenning is I'm getting a blank page but when I click the refresh button I will then see the list of links. Any ideas are greatly appreciated.

Thanks.
Pol