The source code version of unreal with visual studio runs significantly slower then developing within the editor by itself. Is that to be expected? Is weird to essentially create the whole game in the editor without Visual Studio and only use the source code version for packaging? I also get odd little differences when building from source code. For example my characters capsule collision will be slightly low for the character causing character to hover over ground or particle effects behaving slightly differently then when in editor. I can go in and tweak these things back to normal but it’s odd, are little tweaks like this common? Makes me feel uncomfortable using source code version for much beyond packaging.
Are you running with the debugger attached? (F5 in Visual Studio). If so, that will definitely affect performance. Try CTRL+F5 instead when you don’t need the debugger. Otherwise there should be no performance difference.
Why are you using Visual Studio for packaging? That’s probably the least convenient method there is. Compile UnrealFrontend from the VS solution and run it - from there you can set up cooking and packaging profiles so you can do repeated builds with one click.
As for other differences between the source code and launcher version, I don’t know, I haven’t experienced this myself. It could be that the build configuration (Debug/Development) has some subtle side effects caused by some macro or #ifdef. If so, that would be a bug, so you should report that if you can make a test project to reproduce it.