[LyX/master] Reduce the amount of needed boost headers

[Jean-Marc Lasgouttes]

Le 10/12/2020 à 13:42, Yuriy Skalko a écrit :
>> Note that, as shown in the new last line, removing lexical_cast _and_ 
>> signals2 is the big win here.
> 
> Here is the first step -- removing lexical_cast.

Patch 1 is fine.

Patch 2: did you try to determine whether to_string() is better than 
using ostringstream<< ?

At least some time ago, performance was better with lexical_cast:
https://www.boost.org/doc/libs/1_49_0/doc/html/boost_lexical_cast/performance.html

JMarc