Thank you for response BlueHazzard.
Today somehow it took 'only' 40 sec.
I checked the build log. It included a lot of warning from my included headers (from that library).
After changing '-Weverything' to '-Wall' in build options it did only show warnings for my file.
After changing this building took only 2 sec.
with this build log is:
Cleaned "myproject - Debug"
-------------- Build: Debug in myproject (compiler: LLVM Clang Compiler)---------------
clang++ -Wall -g -fexceptions -I/home/username/Downloads/libs/libraryname -c /home/username/Projects/CodeBlocks/myproject/main.cpp -o obj/Debug/main.o
clang++ -L/home/username/Downloads/libs/libraryname -o bin/Debug/myproject obj/Debug/main.o -lraryname /home/username/Downloads/libs/libraryname/libraryname.a
Output file is bin/Debug/myproject with size 22.18 MB
Process terminated with status 0 (0 minute(s), 2 second(s))
0 error(s), 0 warning(s) (0 minute(s), 2 second(s))