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Let’s look at serious scientific and high performance production grade software

C++ tensors + grad PyTorch
C++ tensors + grad TensorFlow
C tensors numpy
C++ random forests XGBoost
C++ computer vision OpenCV
C++ statistics, MCMC Stan
Fortran/C/R math R
C/C++/Julia math Julia
Matlab/Java/C/C++ math Matlab
C CPython, default Python interpreter
C++ molecular simulation Gromacs
C++ solid engineering simulation and 3D modeling Solidworks, Autocad
C video processing ffmpeg
C++ video processing gstreamer
C++ audio processing google/mediapipe
C++ GPU parallel algorithms CUDA
C++ game engines (physics simulation, business logic, networking) Unity, Unreal Enigne
C++ web servers Erlang VM, Node.JS/V8, HHVM
C++ Google data warehouse (GFS, BigTable, MapReduce)
Java/Scala open source data warehouse (HDFS, Hadoop, Kafka, Spark)
C databases PostgreSQL, Redis, Memcached
C++ databases MySQL
Go time series database InfluxDB, they considered C/C++ though
C productivity tools MS Excel, Google Chrome, Firefox, Photoshop
C geo algorithms uber/h3
C++ geo algorithms google/s2
C++ original Google Maps

UPD: 2020-06-08

C++ SpaceX software in rockets
C++ Tesla is likely to run C++ and Go github

UPD: 2020-12-29

C++ Zoom is running C++ servers for their video pipeline

C++ is leading by a large margin. Its ecosystem is astonishing. Pretty much everything of significance has been written and maintained in C++. Bare in mind, other languages like Golang or Rust have been around for around 10 years, still main applications did not migrate to them. Even more, TensorFlow itself is not in Golang, even though they are both from Google and Tensorflow created 6 years later. It is true that Golang is having momentum in service development — things like networking, ORM, business logic — yet it is used in not much anything else.

Some languages was made by mistake (Javascript), some languages are too minimal (Golang), some are not scalable (Python). Maybe, then C++ has plenty of good besides performance? It has first class OOP, generics, operator overloading, standard library, gRPC and Apache Thirft, with RAII memory leaks are rare. Where I am going with this? If you are going to write high performance software likely it is going to be in C++.