[warfangle]

I've run into similar issues. It seems to be the draw speed that is very slow. Each 80char line takes a good 10ms to render, which when working with a fast command that outputs a lot of text... The command will have been done for thirty seconds while eshell is still sputtering along showing output.

This is especially noticible with my on-modified-run-tests script - if there is a long stack trace, often times it's faster to kill the task and start it again rather than letting it finish.

[chriswarbo]

If the output is getting parsed in some way then it can get really slow. For example, automatic highlighting of matching-parenthesis is great 99% of the time, but can hang the process for several minutes on large outputs (eg. a MySQL dump of serialised PHP objects).

On a related note, the "clear" function at http://www.khngai.com/emacs/eshell.php can help speed things up when your buffer gets large; it's basically like "reset" in bash. The reason it's useful is that the shell prompts in an eshell buffer are marked as read-only, so trying to clear a region containing prompts will fail. I'm sure there are other workaround for this, but running a "clear" command is easy enough :)

[warfangle]

Nah, no automatic highlighting or anything of that sort - just the raw, default, eshell.