Forking this from  Issue 700928  to avoid jamming that bug that is about wired memory.

Another thing I noticed while looking at avi's trace in  crbug.com/700928#c25  is that the gitiles blame tab is using 67 MB for the v8 heap.
However, I just checked and gitiles doens't seem to have any <script> nor any <iframe> at all.
In fact on my machine I always get ~4 MB for its v8 heap (which I think is the bare minimum one gets just for initializing v8).

So, avi@, I think some extension is injecting JS into your tabs.
No idea how much that is impacting overall, but definitely something is happening there.

If you have spare cycles, could you grab a trace consisting of a brand new chrome instance where you only have gitiles blame open, and another instance where you do the same in incognito?