The software portal takes a long time to load in version 8.5 of Software Management. If you scroll through the available software, it can take a long time to render more available software.
This is a known issue.
First, check this KB to ensure it is not a commonly known configuration issue: TECH161630
This issue is fixed in 8.5 RU3. If you are using 8.5 RU2, you can use the attached revised stored procedure to resolve the issue.