Number of translation units: x. Total translation unit size: x bytes.
Number of files: x. Total file size: x bytes.
Legend
Translation Unit
The data processed during a compiler invocation.
Individual Size
The size of the file, and as a percentage of the total file size.
Expanded Size
The size of the file and all the files it includes, directly and indirectly. Also shown as percentage of the total translation unit size.
Added Size
How much size is added by this file being part of the build. In other words, if this file were empty and had no includes, how much smaller would the build be. Also shown as percentage of the total translation unit size.
Occurrences
How many translation units this file is part of. Also shown as a percentage of the total number of translation units.
Include Count
How many times this file is included directly.
File size does not correlate perfectly with compile time, but generally serves as a rough guide to what files are slow to compile.