The test

testlibrary_tests/ir_framework/tests/TestDFlags.java

runs 11 separate IR framework runs by enabling only a single property/D flag in each run. This seems like a waste of resources for just a sanity run (we don't do any additional verification). Moreover, some newer property flags are missing.

I suggest to cut it down to 2 runs:
- IR verification enabled (i.e. -DVerifyIR=true, which is the default)
- IR verification disabled (i.e. -DVerifyIR=false)

In both runs we simultaneously set all property flags to there non-default value as a sanity test.

This reduces the test execution time from around 20-30s down to 3-4s.