Which Space Client?
The Space virtual world can be entered via your browser with no plugin.
The web version is perfect for fast access and viral marketing.
Anyone can jump in instantly and everyone can share urls and embed code for different regions.
The desktop version can be downloaded free here http://sine.space/
It offers much higher performance than the browser version; you should expect the frame rate to at least double.
It also supports better graphics; better lighting, shaders and visual effects, giving you the full AAA experience.
The desktop application has a bigger cache so you do not have to download a region every time you log in.
And it has some unique features, like VoIP and the clothing customisation editor, which are not currently supported in the browser version.
COMING SOON (Ask a developer in the community skype chat for a copy!)