How do I speed up incremental builds with GCC for C++?

Incremental builds in C++ using GCC can become slow due to several reasons, including increased file sizes and inefficient dependency management. To speed up the build process, consider the following optimization techniques:

1. Use precompiled headers: Using precompiled headers can drastically reduce compilation times, especially for large projects with many dependencies.
2. Limit the number of included files: Reducing the number of headers included in each translation unit can help minimize the amount of code GCC needs to process.
3. Optimize makefile: Ensure that your makefile is correctly set up to reflect dependencies accurately. Avoid using wildcard patterns that could cause unnecessary recompilation.
4. Use separate compilation units: Splitting large source files into smaller ones can allow GCC to compile only the parts of the code that have changed.
5. Enable parallel builds: Use the '-j' flag with make to allow parallel jobs. This can significantly reduce build times on multi-core machines.

        // Example Makefile optimization
        CC = g++
        CFLAGS = -Wall -Wextra -O2
        OBJ = main.o module.o utils.o
        TARGET = my_app

        all: $(TARGET)

        $(TARGET): $(OBJ)
            $(CC) -o $@ $^

        %.o: %.cpp
            $(CC) $(CFLAGS) -c $< -o $@
        
        clean:
            rm -f $(OBJ) $(TARGET)