[jed-users] del_region() tremendously slow

[Morten Bo Johansen <mbj@xxxxxxxxx>]

Hi,

I just happened to stumble into this rather abnormal use case: mark and
delete about two million lines in a file. With del_region(), it takes about
8 seconds to do so on my oldish computer. With the competition (Emacs), it
happens in the blink of an eye. Why is del_region() so slow?

The following function does the job in 1 sec flat - still slower than
Emacs, but 8 times faster than del_region():

  define delete_region()
  {
    variable reg_end;

    ifnot (is_visible_mark)
      return flush("no region is marked");

    check_region(1);
    reg_end = what_line;
    exchange_point_and_mark();

    loop (reg_end - what_line())
      delete_line();

    pop_spot(); pop_mark_0();
  }

If this function doesn't deviate from the intrinsic function in its workings
or has some other shortcomings unbeknownst to me, why not just make this a
library function in site.sl and call it del_region to replace the very slow
intrinsic?

I know it is an abnormal use case, but still ...

Regards,
Morten
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