A rule project takes longer to build once migrated from Rules for .NET 3.x to Rules for .NET 7.x.
In 7.x gap checks are enabled by default for all decision tables and the checking computation has been improved, for example it verifies gaps in domains. The additional checks can significantly affect the build of large decision tables.
Resolving the problem
Disable gap checking for decision tables.
Since the gap check is set per table, you need to change the gap check property on all decision tables in your project.
Attached is a program that modifies all decision tables under a certain directory (and sub-directories).
You run the program with the command "DeactivateCheckGap.exe PATH", where PATH is the root directory containing all the decision tables to update.