Alan Mackenzie writes: > The branch scratch/accurate-warning-pos now bootstraps. (It also now > runs on optimised builds. ;-) > > Its bootstrap is a mere 7.1% slower than master's. Hi Alan, Great progress! There are clearly benefits to Emacs Lisp programmers (especially if errors and debugger backtraces can someday have accurate source positions), to be weighed against the cost of a slower Emacs for all the non-Lisp programmers and non-programmers who work with Emacs. I don't know how to begin to sort that out, but since I've been working on creating a benchmark suite for Emacs, I'm thrilled you've given me such an interesting test case. :) Here's how much longer in percentage terms the tasks in my nascent benchmark suite take in your branch compared to 5b218be0c3, the commit your branch is based on, running on my newish Linux laptop. I'll push my benchmarking project to a scratch branch soon so you can see the code which was benchmarked. cus-theme-tasks-load-tango: 9% bytecomp-tasks-compile-doc: 24% kmacro-tasks-edit-lines: 18% fill-tasks-fill-paragraph: 15% cmds-tasks-forward-line: 5% data-tasks-prime-p: 1% emacs-tasks-startup: 4% syntax-tasks-backward-word: 23% syntax-tasks-forward-word: 20% Here's a benchmark report, which contains the measurements from which I calculated those percentages: