TikiWiki has a massive codebase compared to many other CMS's and as such requires more PHP memory. These links offer guideance on getting TikiWiki up and running:
- http://doc.tikiwiki.org/Requirements+and+Setup
Discusses all version requirements and configs needed for running TikiWiki.
- Article 82
Details the PHP memory_limit issue and offers solutions.
- TikiFriendlyHosts
Hosts that are known to work with TikiWiki, some offering support, hosting and even automated installations.
Note: Not all hosts which use the automated CPanel/Fantastico actually have PHP set to more than 8Mb.
- TikiBoosting
If you run your own web server, this document offers insight into getting Tiki to run faster.
If you do need to move your TikiWiki to another server this guide could help: MoveTikiToAnotherServer
Cheers