The responsiveness of the design page for large systems (>500 kW) mainly depends on the following factors:
type of inverter (multiple-MPPT, microinverter, single MPPT multiple-string)
number of surfaces
laptop/PC specs (RAM and GPU)
The following tips can help improve the design experience:
Use the pre-positioned panel layout to create the panel layout before setting up the inverter design https://solarplus.atlassian.net/wiki/spaces/V5HC/pages/2295627816/Panel+Layout+and+Map+Tools#3.-Create-a-%E2%80%98panel-first%E2%80%99-layout-(optional-for-initial-layout)
When there are more than 15 trackers you will see an additional 'Sync pause/resume' button in the toolbar. This also allows you to refine panel placement without lagginess as it suspends the reports of 'panel count per tracker per surface' which is where most of the processing delays occur.
