You can select Performance options by clicking on the "Menu" button on the top bar and selecting the "Options" button on the popup window.

Local Storage allows Stratheon to store an amount of calculated terrain information locally. This can greatly increase the speed of loading terrain on planets you visit often. To increase the amount of space Stratheon can use for this storage, select the amount you want to increase by and click the "Increase Storage" button. You will be presented with a dialog from Silverlight, asking you to confirm the new higher storage amount. Click OK on this dialog.