Loading QML files in 5.9 causes much higher memory consumption than in 5.6

I have compared memory consumption of a test case that loads 1000 different QML types using branch origin/5.6 with this patch from QTBUG-61536: https://bugreports.qt.io/secure/attachment/64728/0001-Fix-memory-of-QML-type-registry-not-freed-when-clear.patch and latest origin/5.9 branch where all those patches were merged.

According to TC-Malloc (Bytes in use by application), there is a big difference between Qt versions:
In 5.6, the total memory consumption grows by 2 MB from 30.5 to 32.5 MB
In 5.9, the total memory consumption grows by 30 MB from 31.5 to 61.5 MB

It looks like 5.9 could have a regression that causes high memory consumption when types are loaded.

See test project and valgrind log (difference between loading 9 and 107 types) attached.

Steps to use the test project (only tested on linux):

• install tcmalloc and/or valgrind
• ./generate.sh 2000
• to use tcmalloc: qmake CONFIG-=valgrind
• to use valgrind: qmake CONFIG+=valgrind .
• make
• ./run Test.qml
• click on small yellow rectangle to run GC and trim component cache
• click on small green rectangle to print tcmalloc or valgrind memory stats
• click on white background to start loading
• wait until 1000 components were loaded, then click on white background to stop loading
• click on small yellow rectangle to run GC and trim component cache
• click on small green rectangle to print tcmalloc or valgrind memory stats
• you can click red rectangle to clear component cache as well