If I type begin<Ctrl+Space> in Latex-mode, my CPU graph peaks for 20 seconds until a dialog pops up. Eclipse is unresponsive during this time.
I use Indigo Service Release 2 and Texlipse 1.5.0 on Debian Wheezy with openJDK 7.
I noticed that Ctrl-Space reacts quickly at the beginning of my file. However, the chapter I'm working on has 22000 words and 4300 lines. I assume Texlipse doesn't work well with large files.