Chrome JS is one of the largest consumers of memory in B2G. Leaving aside B2G's worker threads (bug 864927, bug 864931, bug 864932), we spend about 8mb of memory on chrome JS in the B2G main process. We ought to look at reducing the amount of JS we run in the main process, in an attempt to reign in our memory usage. We can use this bug for investigation and then spin off concrete pieces of action into blocking bugs.
Created attachment 740985 [details] Memory report from b2g18 with jsloader.reuseGlobal disabled In this memory report, JS uses ~2x as much memory, but at least you can see where it's going. I have no idea how representative this report is. A better approach would be to try b2g on trunk with zones enabled and jsloader.reuseGlobal set to false.
Rolling dependencies up into Bug 797189 (Operation Slim-Fast), and closing this one out as it's very broad and doesn't look like it's caught on as an active meta. Resolving as INCOMPLETE for lack of a better option.