Purpose

This document's purpose is to point to common and easy ways to make a Plone site faster. It's not meant to be exhaustive nor include detailed instructions.

The "hard" part of making a Plone site faster is not mentioned here: use a proxy/cache in front of the Zope instance. This is a complex topic, which involves other pieces of software outside the Plone/Zope world, and is covered in other places.

Profiling and benchmarking

First you'll need to setup some tools for profiling and benchmarking. You need some way to tell whether your attempts to improve performance are working or not, and you need to know what is really consuming time.

ab -c 5 -n 100 http://127.0.0.1:8080/somesite

Install collective.remove.kss

Install collective.remove.kss add-on to remove KSS, which does all the Ajax stuff inside Plone. Beware this will remove some functionalities (check the add-on page for a list). Ajax operations are expensive, so it is often worthy to remove them.

Install archetypes.schematuning

Straight from archetypes.schematuning entry on PyPI:

This package speeds up Archetypes Schemas and is a patch for Products.Archetypes. It uses plone.memoize to cache Archetypes Schemas instead of factoring and modifying them every time its accessed.

Make images in skin layers cacheable by the browser

For each image residing inside a skin layer folder, add a correspondent .metadata file (i.e myimage.png.metadata) containing:

[default]
cache=HTTPCache

Use the CSS and JS registries

Do not add links to CSS and JS files directly on your page templates. Use the CSS and JS registries instead. These tools merge the resources, reducing the number of HTTP requests. And it handles caching as well.

Minimize number of requests and "404 not found" errors

Related to the previous topic, you should care to minimize the number of HTTP requests, because it's expensive in Zope. CSS and JS registries can be used to do just that.

From Profiling Plone and tuning add on product performance (by Mikko Ohtamaa):

Make sure that you don't get any HTTP Not Found 404 pages, since they are very expensive in Zope. You can log not found pages if you clear "NotFound" in error_log / "Ignored exception types".

You can use the Firebug's Network panel to find 404 errors and to see which resources are requested by the browser when opening a URL on your site.

Move processing from templates to view classes

From Profiling Plone and tuning add on product performance (by Mikko Ohtamaa):

Move template expression (python:, string: and traversing expressions) to BrowserView methods, since template expressions are run under RestrictedPython sandbox which comes with heavy execution penalty.

You can use PTProfiler to see which expressions are more time consuming.

Use plone.memoize

From Profiling Plone and tuning add on product performance (by Mikko Ohtamaa):

Check plone.memoize product which contain function decorators for caching the function value during subsequent function runs. This is easy way to solve the problem if a heavy function or view is called several times per request.

Use Zeo

It's often said that use a Zeo server is always a good idea, even if you have only one Zeo client. Read the chapter Scalability and ZEO of the Zope Book for more details.