The project that I work for is Chromium.

Its codebase is really huge. (~30 000 000 lines of C++ code)

Until qtcreator 4.3.x or 4.4.x (I'm not sure) everything was Ok.

Starting from 4.5.0 clangbackend consumes a lot of memory.

(The more files I open, the more memory it consumes)

When there are only 20 typical c++ files openned the memory consumption of a clangbackend process grows up to 3-4.5 Gb of RAM.

So I ran clangbackend using valgrind tool named "massif".

Plz take a look into its output in the attach (usage: ms_print massif-file).

I can see allocations of various clang/llvm objects.

I'm not experienced in llvm but have a good knowledge of C++.

If you need more information please feel free to ask me. I'll help.