Under the guidance of Kohei Yoshida and Markus Mohrhard, I have been working to shorten the time it takes to open an ODS file. These shorter load times may be more noticeable depending on the content and size of the file that is being loaded. Although this work should result in all ODS files having at least a small improvement in load times, let's take a look at a couple of extreme cases.
Please keep in mind these are not rigorously, scientifically performed tests. They are just to give an idea of the improvements we are making. I did these tests on a machine with a 3.2GHz AMD Athon 64 X2 Dual Core Processor 6400+ and 8GB of RAM running 64-bit GNU/Linux. I used LibreOffice 3.5.4 and the latest build of my feature branch which gradually gets merged to master (LibreOffice 3.7).
Test 1 used an ODS file with a single sheet containing 10,001 rows and 149 columns of numbers and simple formulas. LibreOffice 3.5.4 takes 20 seconds to load this file, and LibreOffice 3.7 takes 16 seconds. That's four seconds quicker which is a 20% reduction in load time. Ok, that's not bad.
Test 2 used an ODS file with a single sheet containing 5,230 rows and 189 columns of matrix cells with complex formulas. LibreOffice 3.5.4 takes 26 seconds to load this file, and LibreOffice 3.7 takes 13 seconds. That's 13 seconds quicker which is a 50% reduction in load time!
Also, take a look at Kohei's post to see some other awesome ODS load time improvements made last year. (I attempted to mimic his format for the load time charts and drew inspiration for my whole blog post from his post.)
So we've made progress, but we are all continuing to work to improve LibreOffice for a better user experience.