Depending on how you create your queries, custom queries can have an impact on the performance of your system. In your custom query, when you create an Association Filter, you want to avoid using –Any– for the module selection and avoid All for the business object selection. The reason to avoid those particular selections is that they can cause potential report performance issues. This is mentioned in the IBM TRIRIGA 3.4.2 Reporting User Guide. It is better to specify a specific association type in your Association Filter than to use –Any–.
If you have any fields that have a special character in them, like < > , & * or -, that can also impact your performance. While field names should not have < > , & * or – in them, it could happen somehow. If any of your fields manage to have special characters in them, then this is going to cause an issue, because the reports will not be built. So it is a good idea to avoid special characters. If you do have special characters in any of your field names, it is best not to have it referenced in a query. But, ideally, you will want to create field names that do not use a special character.
It is important to note that if you have modified your custom queries, you need to clear the Query Cache in the TRIRIGA Admin Console for the change to take effect.