Subject: Re: bug#29279: Sharing the margins

From: Dmitry Gutov <[email-masked]>
Date: Mon, 13 Nov 2017 21:33:08 +0200

On 11/13/17 9:22 PM, Eli Zaretskii wrote:

>> Still, it seems unnecessary if the somewhat faster C code could
>> implement that for every user.
> 
> We could add that later if needed.  It's not rocket science, it's just
> more complexity.

Yup.

>>> posn-at-point goes _once_ from window-start to the specified position,
>>> so on average it traverses half a window, once.  By contrast, we are
>>> now talking about redisplaying the window twice, and one of these 2
>>> times must traverse the entire window.  So we are talking about
>>> threefold slow-down on the average.
>>
>> 3-fold slowdown from 500 FPS seems acceptable to me.
> 
> For each redisplay cycle?  On top of disabling most redisplay
> optimizations?  I doubt that.

Hard for me to tell. Like, in the recent discussion of a performance 
problem related to double-buffering, apparently Emacs itself wasn't the 
rendering bottleneck.

You probably know better, though.