A chart with multiple chart lines takes a long time to create because every time a chart line is added, CFX-Post re-reads all of the transient files to extract the relevant data.
CFX-Post doesn't allow the definition of multiple chart lines at once, and doesn't give the user any control over when it should re-read the transient data (which can take a long time if the run has a large number of timesteps.
No workaround is currently available.
ANSYS CFX Release 11.0 Update 1. For this update, a "Refresh" button has been added at the top of the Chart Viewer. The only times that CFX-Post will read the transient data is if the user presses the "Refresh" button, or if the chart is printed or the report is previewed or updated and CFX-Post determines that the chart data is out-of-date. Whenever CFX-Post determines that the chart data is out-of-date, it adds a note for the user next to the "Refresh" button: "To update the Chart, press Refresh". Note that the documentation for Update 1 has not been modified to take account of this functionality.