Regression in 0.31.2 compared to 0.30.0 calculating reporters

[rhpijnacker]

After upgrading from 0.30.0 to 0.31.2 I noticed that it takes much longer to calculate derived prices, which I calculate using a reporter.
What takes 10 seconds on 0.30.0 takes possibly 10 minutes on 0.31.2.
For now I reverted back to using 0.30.0.

[Flix6x]

This is due to #2060. It will be fixed in the next release, regardless of whether that will be a patch or minor release. Apologies for the regression. A workaround is to upgrade timely-beliefs to the latest version.