The slowness is caused by the syntax highlighter. Chrome's view-source:
attempts to highlight the whole file at once, which takes some time on a 1.5MB file.
Press Shift + Esc to show Chrome's Task Manager, and you will see that the CPU shoots up on "view source". If you wait a little longer, the "Page(s) Unresponsive" dialog will show up (as shown below).
This bug has been reported before at https://code.google.com/p/chromium/issues/detail?id=128293