When holding a great number of entries in your data source it is a best practice to compress them to avoid slowliness issues when using your data source. The Data Source (Optimize) will analyze all your entries, compress them and then resave them, thus saving space in your data source.
Administration - Pack Data Source (Optimize)
1. Open the data source you wish to optimize. In Administration click on Pack Data Source (Optimize) and then click on Analyze.
Pack Data Source - Analyze
2. Once the Analyze is completed click on Optimize to proceed with the optimization of your data source.
Pack Data Source - Optimize