Re: another example of org being slow, with some analysis

[Jacob Nielsen <jacob.nielsen@alcensoft.com>]

Nick Dokos <ndokos@gmail.com> writes:

> Eric S Fraga <e.fraga@ucl.ac.uk> writes:
>
>> On Friday, 19 Jun 2015 at 08:19, Daniel Bausch wrote:
>>
>> [...]
>>
>>> Line 6000 is indeed quite "lame".  I have similar problems like Eric.  A
>>> table recalculation at line 43868 takes about a minute at my quite fast
>>> machine.  I also tracked that down to org-current-line.  One interesting
>>> detail is that this depends on the buffer encoding.  With ASCII the
>>> recalculation takes less than a second, with utf-8 about a minute.
>>
>> Adding some data: my table is at line 8438 in the buffer but character
>> position 398345 (I have very long lines as I use visual-line-mode in org
>> exclusively with org-indent).  I do use utf-8 encoding.
>>
>> I have just tried updating the table on a different laptop (i7-2760, 8
>> cores, 8 GB RAM, Ubuntu) and it was very fast.  
>>
>> The two laptops are running different versions of emacs (tracking latest
>> emacs developments on Ubuntu and Debian testing lead to different
>> versions unfortunately) so my gut feeling is that there is an emacs
>> issue here and possibly one related to utf-8 as Daniel suggests.
>>
>> I'll try to do more instrumenting on my other laptop when I get a
>> chance.
>>
> What is the setting of cache-long-scans you are using? Does it differ
> on the two laptops?
>
> Ivan Andrus suggested setting it to nil, but it seems that for this
> case, leaving it at t (the default) should be much faster. But there
> may be a bug in the cache code.

It *should* be faster but it isn't :-( At least not when using org mode.

I've had this in my org file where I recalculate tables regularly.

# -*- cache-long-scans: nil; -*-
# This makes forward-line much faster and thus org-goto-line and thus org-table-sum (C-c +)

Before it took forever to recalculate tables; now it's fast :-)

Org mode file with 10500 lines. The tables I recalculate are at the
bottom. Current org mode version is 8.2.10 (org-plus-contrib 20150601)

Best regards,
Jacob