I switched to nightlies from RC2 after the following fix was merged to address the horribly slow installed applications page:
https://github.com/truenas/middleware/pull/8075
https://jira.ixsystems.com/browse/NAS-113987

The loading of the installed apps page is improved in nightly, but the issue also seems to the upgrade app screen, which hasn't improved.

To Reproduce:
0. Prerequisite: Have Truecharts catalog installed
1. Refresh all catalogs under Available Applications (also takes a very long time)
2. Switch over to Installed Applications,and identify in app with "Update Available" shown
3. Click the app's menu button and select Upgrade
4. *Wait over a minute for the upgrade screen to appear*
5. Click upgrade and then the minimize tab
6. Repeat painfully slow process for other apps with available update (since there is no bulk update option)

I have attached a recording of this to better illustrate just how slow it is to load the upgrade screen for a single app (about 1min 25 sec).

System:
-25 applications installed
-Truecharts & Official catalogs