To Much Different build time on same machine

Hi, Dear Community ! I have one problem with hot reload my code project - To Much Different build time!
Sometimes it is about 40 seconds, but sometimes it is about 7-8 seconds !
I completely understand the difference between building entire solution and building my project. And I build always only my project.
I DO NOT change any setting inside UE Editor or Visual Studio .
and I DO NOT add a lot of code. Project is done. But, for example now building time is 7 sec and visual studio works very fast. But tomorrow, when I will lose my internet connection visual studio is very very slow . When I click build my project visual studio looks like it thinking about anything and make it’s job step by step but very very slow.
When I will obtain my internet connection again and restart UE Editor and Visual Studio then project build time is fast again as it was before …
May be this problem is about some visual studio extensions lilke GitHub Extension ? I have no idea , please help !

Soft - VS2015 Professional + VA X