• make sure the power settings do not use the option to enable cpu throttling (this seems to be a java issue)
• try replacing zends jre by JRE 6 (http://java.sun.com/javase/6/download.jsp)
• disable the OS look&feel in your zend application
• disable all power management for your video card
• if you are using a dual monitor setup, make sure the editor & palettes are on the same monitor/display
• remove the Zend Project cache file : /Documents and Settings/{Win username}/ZDE/config_5.1/caches/
• expand the heap sizes (to more then 256 MB) the JRE needs for the Studio to function [file: {studiopath}/bin/ZDE.lax]
  
• if you have a 64b machine, make sure you have the 64bit java lib
• try disabling your antivirus for a second and check if performance goes up
  
• if you are using an external subversion client (not ZDE’s), make sure your options in ZDE are on CVS. (options > source control). Performance gets a huge boost (integrated svn is causing a problem when using 3th party tools)
  
• submit a support ticket (http://www.zend.com/support) (make sure to mention you tried all t he above steps, and provide as much detail as possible, because they won’t fix your problem untill they have everything they are looking for : hardware, software, ZDE.log, description of the project)
  

Here’s the info I found posted over at the PhpBuilder.com Zend Studio Forum by MStaniszczak (post is no longer there). This item addresses the speed of the java virtual machine, and for those of us running Intel processors, this tends to be faster than the Sun JRE. If you’ve got an AMD processor, this may or may not yield any performance.

Head on over to BEA Systems and get the JRockit 5.0 JRE. Don’t worry about the SDK, unless you’re a Java programmer. It’s about 30 megs, so dial-up beware. After downloading it, extract the exe (right click, extract archive).

After you’ve done that, you should see some files, as well as another archive or zip file named something like win_ia32_jrockit150_04_jre.zip. You’ll want to extract that as well, to it’s own directory or folder (name it jre) , and that’s going to be what we need.

First, make sure the ZDE is not currently running. If it is, exit it. Now, find your installation of the Zend Studio client. It should be something like C:/Program Files/Zend/ZendStudioClient-5.0.0/. You’ll see a directory already named jre. Rename it to jre_old. Copy the directory we created from the archive into the ZendStudioClient-5.0.0/ directory.

For me the HEAP size, in combination with the source control tab (to cvs) did it, as i am using tortoisesvn for version management.