Originally Posted By: BearZDefect
One place where Open/LibreOffice falls short for me is performance. It is very slow. Maybe you don't notice this opening small simple documents/workbooks on fast computers. MS Office is very noticeably faster at almost everything it does, no matter which version - 2003/2007/2010. (I am not just referring to program startup, and I've used both on computers ranging from single core to quad core 8+ GB machines.)
OO, LibreOffice, etc. uses its own format, emulates Microsoft's proprietary format. Will always be a performance hit during conversion. If you do your work in OO or LibreOffice default format locally, performance will be better. Then "save as" the format you want when your ready to send.