If the ST_DATA.MDB file on your hard drive gets exceedingly large, it can take much longer to open / access the system tester. It essentially has to read this file into memory before it can do anything else. The file can potentially get as large as 2GB in size. If you want to check the file size first, ST_DATA.MDB will typically be located in C:\Users\(Windows.Username)\AppData\Local\Thomson Reuters\MetaStock\(MetaStock version number)\Formulas 2GB is a limitation of Microsoft Access databases. Typically if the database gets cleaned regularly / heavy optimizing is not done the file stays manageable. There is a clean ST_DATA.MDB file that is kept separate that you can revert back to, but you would lose any custom system tests you might have created (the location would depend on which MetaStock version/eod/pro you have). Additionally, you can attempt to run the JETCOMP.EXE application which will attempt to compact / repair the MDB file outside of MetaStock (the location of jetcomp.exe also depends on which version/eod/pro). *Before running jetcomp.exe you would want to rename your ST_DATA.MDB file to ST_DATA1.MDB. After doing so, run JETCOMP.EXE When "..." browsing for the Source file, browse to the folder containing ST_DATA1.MDB and double click the file When "..." browsing for the Destination file, browse to the folder containing ST_DATA1.MDB and double click the file Remove the 1 from the end of the destination filename, making it ...\ST_DATA.MDB and click the Start button which should attempt to compact / repair the System Tester file. At that point you can double-check the size of the new ST_DATA.MDB file. In some cases it may not be able to compact the file that much. At that point you may want to try and access the formula organizer from within MetaStock and Export any custom System Tests you might have. You would then be able to import them into a clean ST_DATA.MDB file. If the file is of a reasonable size again (~300 MB or less) you should likely be able to go back to using it normally again. You may want to consider manually backing up your formulas or using the "Options-->Clean Now" button within the System Tester to keep the file in a more compact state.