Having experienced incredibly slow exports of layouts with all versions of Pro (now on 2.8.3), even with all data being local, I decided to see how a python export script performed. In this particular case, it was just taking a few minutes to export via the GUI and not twenty (although I've had it take even longer with complex layouts!), but still painfully slow. I did a bunch of tests, and here are the average export times for this particular layout:
Export time via the Pro GUI: 2 minutes 55 seconds
Export time via the Python window: 22 seconds
So Python was 8x faster! And when I experimented with some exports of maps with raster data (heat maps), the difference was even more pronounced-- almost 3 minutes vs 12 seconds.
I guess I'll be digging in to python export options for a bit, at least until the Pro GUI can handle exporting my layouts in a more timely fashion.
Here is the code I used:
aprx = arcpy.mp.ArcGISProject("CURRENT")
for lyt in aprx.listLayouts("TestLayout"):
lyt.exportToJPEG("C:\...\Maps\PythonExport_HeatMap", 200)