Re: `make-overlay' very slow

[Lennart Borgman]

On Sat, Apr 11, 2009 at 8:11 AM, Werner LEMBERG <address@hidden> wrote:
>> overlays have a poor algorithmic behavior (many operations take a
>> time proportional to the number of overlays in the buffer).  Better
>> use text-properties (which are implemented with a tree and should
>> provide something closer to O(log N) complexity instead).
>
> I did that (see attachment for reference), and it really works at a
> reasonable speed.  However, it is the completely wrong concept since
> it sets the `modified' flag and stores undo information,

There is a macro in font-lock.el that you can use to modify text
properties without storing undo information or setting the modified
flag.

> and it fails
> with modes which use the `invisible' and `intangible' properties.