bug#32159: 26.1; inhibit-compacting-font-caches does not fix all fonts lagging issue

[net june]

On 07/16/2018 02:53 AM, Eli Zaretskii wrote:
>> Date: Sun, 15 Jul 2018 09:50:03 -0700 (PDT)
>> From: Drew Adams <drew.adams@oracle.com>
>> Cc: 32159@debbugs.gnu.org
>>
>> It's great to support a large variety of fonts.  But
>> if a user has lots of fonts installed then it seems
>> that such an advantage can become a debilitating
>> (i.e., severe) disadvantage.
> 
> Only if some characters Emacs needs to display are not supported by
> any of those many fonts, and if the user didn't customize Emacs to
> tell that he/she doesn't _want_ those characters to be displayed,
> ever.  How reasonable is such a situation?  Not very reasonable from
> my POV.
> 

Is it possible to save the font search result to file (custom file) for 
next use? Then we just need to open the HELLO file once to cache the result.