Just to warn people! Do NOT remove languages in Mavericks, I did this on most of the former OS X versions without any problems but it seems Mavericks is different. I removed all non English Languages in Apps and the whole system before but this time many Applications just crash upon opening or do not work properly, example, Terminal opened but crashed instantly, after copying the App from a backup it worked again, Mail opens but it won't display any content from any mail you get, I again copied from a clean System and it works again. This never happened on Systems from 10.0 b to 10.5.8 and Mountain Lion, I skipped Snow Leopard and Lion so I can't say if this was also the case for those OS X versions. So, especially for people who use Apps that remove languages, be careful, it might damage your system.