just to let you know that we have made a range of performance fixes in version 2.29 and 2.30 over the last month. The performance fixes are related to:
Saving of aggregate data values during data entry.
Analytics query optimizations, affecting dashboard, pivots, chart.
Fixing an incorrect cache configuration, leading to faster metadata loading.
If you are managing a high-volume DHIS 2 instance it can be a good idea to upgrade to the latest 2.29 or 2.30 build.