
George Ou
compares Microsoft Office 2007 to OpenOffice 2.2 in memory and CPU usage using the OOXML and ODF file formats. The conclusion according to Ou:
"We can see that the OpenOffice.org ODF XML parser (while vastly improved) is still about 5 times slower than Microsoft's OOXML parser. OpenOffice.org also seems to consume nearly 4 times the amount of RAM to hold the same data. While OpenOffice.org continues to have fewer features than Microsoft Office, it continues to consume far more resources than Microsoft."