If your system is slowed down when displaying Trends that show historic data, you should check the historic configuration settings of the relevant points. The point configuration settings define the amount of historic data that is to be logged - if ClearSCADA is set to log an excessive amount of historic values, this may cause slow performance.
If the points are configured correctly, you should check for duplicated historic data. Although rare, it is possible for faulty outstations and faulty drivers to duplicate the historic data for points. This can cause slow performance when viewing historic data for points (on Trends and other displays) as the system has to process excessive amounts of historic data.
You can set your system to remove duplicated historic data by using the Start Historic Optimization method, see Historic Optimization. This method can be configured to be performed upon user selection on a Mimic or according to a schedule.
Further Information
Configuring Mimic Animations: see Animations.
Schedules: see Using Schedules to Automate Regular Functions.