It seems my Google Chrome cache is here;
Mine is 375MB in size.
It looks like there are some methods to limit it, based on modifying the shortcut for Google Chrome...but are some limitations like the fact that the shortcut is not used when the browser is launched automatically by the system. How To Change Google Chrome’s Cache Location And Size
I've never really noticed Chrome getting slower over time, but I also use an SSD..so maybe that is working around the issue. And I never clean my cache or temp internet files either.