If there's one thing that's really annoying about OpenOffice, it's the fact that it's so darn slow at starting and occasionally just simply freezes due to the large amount of system memory its Java code requires. If this single issue could be fixed, I'd definitely use it a lot more although there still remains plenty of work to do on the usability side of things too. The good news however is that it's not hard to tweak and optimize OpenOffice to achieve some significantly better performance results. Here's three simple steps for starters:
1. Disable Java and Increase Memory Use - If you've got more than at least 1GB of RAM, then this is the simplest and easiest way to ensure OpenOffice opens and operates quicker. Simply go to "Tools" and then "Options". In the "Java" tab make sure that you've disabled the Java Runtime Environment option. Then in the "Memory" tab change the values to "Number of steps: 20, Use for OpenOffice: 128, Memory per Object 20, Number of Objects 20".
3. Enable QuickStarter - On Windows, you have to double click on the quickstarter.exe file in the OpenOffice program folder. On all other platforms, just go to "Tools" and then "Options" and "Enable systray Quickstarter". Quickstarter loads OpenOffice.org code and data into memory ahead of time, so that when you are ready to open a document, some of the work is already done.
Other than these steps, there's not much more you can do but you should experience noticeably better startup times. Hopefully the OpenOffice developers will one day recognize that this is a major issue for most users and implement these tweaks by default.