How to find out what RAM resources are spent on in a browser tab?

Question

Google Chrome

For example, one tab from my Chrome. According to the internal task manager, it consumes 137 MB of memory. The image cache is only 9MB, the JS is 40MB (33MB active). There is also a rendered composite layer for 118 MB, but as far as I know, this is a GPU. And such an approximate consumption ratio for all tabs. What is the remaining ~65% of memory in tabs spent on?
p.s. Windows 10 x64 Chrome x64 v61