A big part was that pascal had a decent module system, while C only has includes. The same header files can be included from multiple places and have to be proc

A big part was that pascal had a decent module system, while C only has includes. The same header files can be included from multiple places and have to be processed multiple times. IIRC the Plan9 C compiler had some restrictions (or maybe just conventions) to prevent this. Also, Borland Pascal / Delphi compilers weren't terrible at optimizing. And they often produced smaller executables.