We recently obtained new imagery for my county and they delivered the images as tiles. There are around 1000 tiles for a 180 square mile county. I created a mosaic dataset, loaded the tiles into that dataset. The first problem I ran into was that only 20 tiles of the imagery were showing at any given time. I found out that was caused by a setting in the layers properties "Maximum Number of Rasters Per Mosaic Dataset." It was initially set to 20. So I bumped that up to 1000. At that point, the entire county would draw, but it was cripplingly slow. It took around 5 minutes to draw the county. I then ran the tools to build pyramids and overviews, however nothing has helped. The performance is awful and basically unusable. I know that what I am seeking to do is possible because my county has a 2016 and 2012 imagery that loads the entire county and works great. I'm just trying to turn this imagery into the same thing so we can roll it out to the rest of our county. I currently have a support call with both ESRI and the Imagery company but both calls have gotten nowhere, so I figured I would try here while I wait on responses from the support agents.
1. Where are the rasters stored? Are they on a network drive?
2. Did you specify the option to build overviews when you added the rasters?
1.5 hours seems very long if you're not building overviews. Try the following: