Updated December 2, 2016
This article explains what to do if the discovered Subnets take a while to load.
All IPAM versions
1. Decrease the number of displayed rows in the tree grid to default value (150) , which will decrease loads.
2. If your are using IE7, upgrade to IE9 or use a different browser.
3. Make more groups and assign subnets to different parents, to reduce size of subnets in one group.