Are long line caches useful?

Do you think this particular FSF Emacs feature is truly useful? I wanted to devote some time implementing it, but then I concluded that it is in 99.99% cases utterly useless, and that I have better things to do with my time. *** Faster processing of buffers with long lines The new variable cache-long-line-scans determines whether Emacs should use caches to handle long lines more quickly. This variable is buffer-local, in all buffers. Normally, the line-motion functions work by scanning the buffer for newlines. Columnar operations (like `move-to-column' and `compute-motion') also work by scanning the buffer, summing character widths as they go. This works well for ordinary text, but if the buffer's lines are very long (say, more than 500 characters), these motion functions will take longer to execute. Emacs may also take longer to update the display. If cache-long-line-scans is non-nil, these motion functions cache the results of their scans, and consult the cache to avoid rescanning regions of the buffer until the text is modified. The caches are most beneficial when they prevent the most searching---that is, when the buffer contains long lines and large regions of characters with the same, fixed screen width. When cache-long-line-scans is non-nil, processing short lines will become slightly slower (because of the overhead of consulting the cache), and the caches will use memory roughly proportional to the number of newlines and characters whose screen width varies. The caches require no explicit maintenance; their accuracy is maintained internally by the Emacs primitives. Enabling or disabling the cache should not affect the behavior of any of the motion functions; it should only affect their performance. -- Hrvoje Niksic <hniksic(a)srce.hr&gt; | Student at FER Zagreb, Croatia --------------------------------+-------------------------------- `VI' - An editor used by those heretics that don't subscribe to the Emacs religion.