Gantt performance was improved in the 6.2 version. In the newer versions, the dev team improved it even more. You can see how it works with 2000 tasks and 5-year scale:
If the performance is worse in your project, make sure that you have the latest Gantt version (6.3.1 at the moment) and the
smart_dhtmlx_rendering.js file is not connected. Since the 6.2 version, the smart rendering is included in Gantt. So, the connected file overwrites the new improvements with the old ones.
If that doesn’t help you, please, reproduce the issue in the snippet, then click on the “Share” button and send me the link: